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More README updates, particularly in regard to DEC's Absolute Loader

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This commit is contained in:
Jeff Parsons 2016-10-22 14:21:33 -07:00 • committed by Jeff Parsons
commit 5d5629c27b
12 changed files with 97 additions and 52 deletions
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8
modules/pdp11/lib/ram.js
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@ -249,6 +249,9 @@ RAMPDP11.prototype.reset = function()
/**
* loadImage(aBytes, addrLoad, addrExec, addrInit, fReset)
*
* If the array contains an image in the "Absolute Format," load it as specified by
* the format; otherwise, load it as-is using the address(es) supplied.
*
* @this {RAMPDP11}
* @param {Array|Uint8Array} aBytes
* @param {number|null} [addrLoad]
@ -261,14 +264,15 @@ RAMPDP11.prototype.loadImage = function(aBytes, addrLoad, addrExec, addrInit, fR
{
var fLoaded = false;
/*
* Data on tapes is organized into blocks; each block begins with a 6-byte header:
* Data on tapes in the "Absolute Format" is organized into blocks; each block begins with
* a 6-byte header:
*
* 2-byte signature (0x0001)
* 2-byte block length (N + 6, because it includes the 6-byte header)
* 2-byte load address
*
* followed by N data bytes. If N is zero, then the 2-byte load address is the exec address,
* unless the address is odd (usually 1). DEC's "Absolute Loader" jumps to the exec address
* unless the address is odd (usually 1). DEC's Absolute Loader jumps to the exec address
* in former case, halts in the latter.
*
* All values are stored "little endian" (low byte followed by high byte), just like the