Merge branch 'master' into gh-pages
This commit is contained in:
Jeff Parsons
commit
d6ad19e2df
36 changed files with 3355 additions and 2743 deletions
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@ -5,14 +5,15 @@ date: 2017-02-28 22:00:00
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permalink: /blog/2017/02/28/
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---
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Since I've more or less achieved all my goals for the PCjs [PDP-11 Emulator](/devices/pdp11/machine/), I've decided
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to turn my attention to an even older historically important DEC computer: the [PDP-10](https://en.wikipedia.org/wiki/PDP-10#Cancellation_and_influence).
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Since I've more or less achieved all my goals for the PCjs [PDP-11 Emulator](/devices/pdp11/machine/),
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I've decided to turn my attention to an even older historically important DEC computer:
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the [PDP-10](https://en.wikipedia.org/wiki/PDP-10#Cancellation_and_influence).
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Having never used a real DEC PDP-10, I've had a steep learning curve creating a [PDP-10 Emulator](/modules/pdp10/).
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So far, the only [PDP-10 Hardware Documentation](/pubs/dec/pdp10/) I've read (or rather, skimmed) is the
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[PDP-10 System Reference Manual (1968)](http://archive.pcjs.org/pubs/dec/pdp10/ka10/DEC-10-HGAA-D_PDP-10_System_Reference_Manual_May1968.pdf).
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To make it easier to create and run some simple [PDP-10 Opcode Tests](/apps/pdp10/tests/), most of my initial development
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To make it easier to create and run some simple [PDP-10 Opcode Tests](/apps/pdp10/tests/opcodes/), most of my initial development
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efforts have centered on the built-in PDP-10 Debugger. In addition to the usual disassembler capabilities, I've also included
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an assembler, so that I can easily enter instruction sequences like this:
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@ -34,7 +35,7 @@ and immediately see the corresponding opcodes:
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It's not a full-featured assembler; it's little more than a brute-force reverse look-up through the disassembler's
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opcode-to-mnemonic tables. But it gets the job done.
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Next, I've written an initial set of [PDP-10 Opcode Tests](/apps/pdp10/tests/) and compared the results to those produced
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Next, I've written an initial set of [PDP-10 Opcode Tests](/apps/pdp10/tests/opcodes/) and compared the results to those produced
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by [SIMH](https://github.com/simh/simh), and so far, so good. More than anything else, that's just a testament to DEC's
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excellent documentation.
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184
_posts/2017-03-21-the-macro-10-assembler-50-years-later.md
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184
_posts/2017-03-21-the-macro-10-assembler-50-years-later.md
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@ -0,0 +1,184 @@
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---
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layout: post
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title: The MACRO-10 Assembler, 50 Years Later
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date: 2017-02-28 22:00:00
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permalink: /blog/2017/03/21/
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machines:
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- id: testka10
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type: pdp10
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config: /devices/pdp10/machine/ka10/test/debugger/machine.xml
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debugger: true
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commands: a 30724 /apps/pdp10/diags/klad/dakaa/MYDAKAA.MAC
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---
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A few weeks ago, I finished my first cut of the *core* PDP-10 instructions in PDPjs. Most of my remaining work
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falls into these categories:
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- UUOs (Unimplemented User Operations)
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- Floating-point instructions
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- Input-Output instructions (eg, BLKI, BLKO, DATAI, DATAO)
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- Miscellaneous instructions (eg, variations of PUSH, POP, JUMP)
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Floating-point is the biggest chunk of work, which I'm going to save for last, with the hope that most PDP-10 software
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didn't use floating-point. However, if all PDP-10 systems included floating-point hardware (which I haven't been able to
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confirm yet), I may have no choice. Floating-point emulation in JavaScript isn't hard -- PCjs already includes an
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[8087 Coprocessor Emulator](/modules/pcx86/lib/x86fpu.js) -- but getting all the details right is time-consuming.
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The PDP-10 has a lot of instructions, and I quickly had far more instructions than I was willing or able to write tests for.
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Besides, any tests I wrote would be based on the same potentially-flawed understandings that I had gleaned from DEC's
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[PDP-10 Hardware Documentation](/pubs/dec/pdp10/). It was obvious that I needed to find a set of DEC PDP-10 diagnostics, much
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like the [DEC PDP-11 Paper Tape Diagnostics](/apps/pdp11/tapes/diags/) I had used to flush most of the early bugs out of my
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PDP-11 emulator.
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Unfortunately, this presented something of a chicken-and-egg problem, because the PDP-10 emulator is still too immature to
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support any simulated devices, even something as simple as paper tape. However, since I did find a series of PDP-10 Model KA10
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diagnostics in [source code form](http://pdp-10.trailing-edge.com/klad_sources/), all I needed was some way to assemble those
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files into binaries that I could load directly in a PDPjs test machine.
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One solution would have been to run a TOPS-10 simulation using the SIMH emulator, assemble the desired tests inside that virtual
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machine, extract the binaries, and then load them into a PDPjs machine. But that would have meant familiarizing myself with
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both SIMH and TOPS-10, and the process of editing, assembling, and transferring binaries to PDPjs would have been cumbersome at
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best.
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### Introducing the MACRO-10 "Mini-Assembler"
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I decided that the shortest turn-around from *assembly* phase to *run* phase (aka *crash-and-burn* phase) would be to
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assemble the files in PDPjs itself. So the PDPjs MACRO-10 "Mini-Assembler" was born. Any machine that includes the PDPjs
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Debugger (like the machine below) now includes MACRO-10 support as well.
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{% include machine.html id="testka10" %}
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The above machine uses the Debugger's assemble ('a') command to assemble DEC's "DAKAA" diagnostic
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[KA10 Basic Instruction Diagnostic](/apps/pdp10/diags/klad/dakaa/) and load the resulting code at address 30724:
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a 30724 /apps/pdp10/diags/klad/dakaa/MYDAKAA.MAC
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The Debugger invokes the MACRO-10 mini-assembler whenever the argument following the target address appears to be a URL.
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As previously described in the section on [PDPjs PDP-10 Opcode Tests](/apps/pdp10/tests/opcodes/), the Debugger already
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allowed you to assemble instructions directly into memory (eg, `a 100 hrli 1,111111`). This "immediate mode" feature is provided
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exclusively by the Debugger; MACRO-10 mini-assembler features are not available in that mode.
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However, one feature that *is* available in both the Debugger and the mini-assembler is full MACRO-10-style expression evaluation,
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since they share the same expression parser. Here are some examples, using the Debugger's 'print' command:
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>> print 27
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23. 0o000027
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Both the Debugger and MACRO-10 start out by assuming a default base (radix) of 8, so the value "27" is evaluated as an octal
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number, and for convenience, the "print" command displays the result in both decimal and octal. You can change the default base
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in the Debugger with the `s base` command (eg, `s base 10`), where the new base is always interpreted as a decimal number.
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This command differs from MACRO-10, which uses the `RADIX` pseudo-op to change the default base.
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Obviously, it would be nice if both the Debugger and the MACRO-10 mini-assembler used matching commands, but the PCjs debuggers
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were written before MACRO-10 support was a consideration, so for now, that's life.
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All of the MACRO-10-style base prefixes are supported (^D for decimal, ^B for binary, an ^O for octal):
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>> print ^D27
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0o000000000033 27.
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>> print ^B1001
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0o000000000011 9.
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>> print ^O1001
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0o000000001001 513.
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Expressions using angle brackets, another MACRO-10 convention, is also supported:
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>> print ^D<45-22>
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0o000000000027 23.
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Note that the base modifier (^D) applies to the entire expression. You can also add MACRO-10 suffixes to integers:
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K: "kilo-", thousands
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M: "mega-", millions
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G: "giga-", billions
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so:
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>> print 5K
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0o000000005000 2560.
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>> print ^D5K
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0o000000011610 5000.
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Binary shifting using a B suffix is also supported:
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>> print 1B0
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0o400000000000 -34359738368.
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>> print 1B17
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0o000001000000 262144.
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>> print 1B35
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0o000000000001 1.
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>> print -1B35
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0o777777777777 -1.
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>> print -1B53
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0o000000777777 262143.
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>> print -1B70
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0o000000000001 1.
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And as the MACRO-10 ASSEMBLER PROGRAMMER'S REFERENCE MANUAL (June 1972), p. 1-17, points out, all the following expressions are
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equivalent:
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>> print 10B32
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0o000000000100 64. '@'
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>> print ^O10B32
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0o000000000100 64. '@'
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>> print 10B<42-10>
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0o000000000100 64. '@'
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>> print 10B<^D<42-10>>
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0o000000000100 64. '@'
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>> print 10B<^D42-^D10>
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0o000000000100 64. '@'
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"Left arrow" shifting is also supported, although the character that the original MACRO-10 manuals referred to as a "left arrow"
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is actually an underscore; later manuals refer to this as "underscore shifting":
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>> print 1_^D18
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0o000001000000 262144.
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>> print -1_^D-18
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0o000000777777 262143.
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Character-based constants are also supported, in the both 7-bit ASCII the 6-bit SIXBIT formats. Use double-quotes
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for 7-bit right-justified character constants and single-quotes for 6-bit right-justified character constants:
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>> print +'SIXBIT'
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0o635170425164 -13255955852.
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>> print +"HELLO"
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0o221054623117 19473311311.
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NOTE: When using the PCjs debugger, the constant must be preceded by an arithmetic operator, otherwise it interprets the
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quoted argument as a string. This is an idiosyncrasy of the "print" command, not the expression parser.
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All MACRO-10 logical and arithmetic operators are supported, including:
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- Unary arithmetic operators (+ and -)
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- Unary complement operator (^-, aliased to ~)
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- Unary base overrides (^D, ^O, and ^B)
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- Binary shifting (B) and underscore shifting (_) operators
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- Logical binary operations (! for OR, ^! for XOR, and & for AND)
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- Multiplication and division (* and /)
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- Addition and subtraction (+ and -)
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- Angle brackets for expression grouping (< and >)
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Much more work is needed to make the MACRO-10 "Mini-Assembler" a general-purpose assembler, but it's already proved itself
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useful in assembling the following tests:
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- [KA10 Basic Instruction Diagnostic #1](/apps/pdp10/diags/klad/dakaa/)
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- [KA10 Basic Instruction Diagnostic #4](/apps/pdp10/diags/klad/dakad/)
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- [Assorted MACRO-10 Mini-Assembler Tests](/apps/pdp10/tests/macro10/)
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*[@jeffpar](http://twitter.com/jeffpar)*
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*Mar 21, 2017*
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