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Added new IBM PC AT configuration (8Mhz model, currently not booting)

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Jeff Parsons 2014-10-13 12:16:27 -07:00 • committed by jeffpar
commit 093099d980
38 changed files with 3848 additions and 1558 deletions
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4
blog/2014/09/13/README.md
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@ -20,8 +20,8 @@ Aside from the additional DMA Controller, other major new motherboard components
The Keyboard Controller and Real-Time Clock/CMOS components required the most tinkering to pass through the ROM BIOS
gauntlet.
For example, at one point, the BIOS ("[TEST.21](../../../../pubs/pc/reference/ibm/static/5170/techref/pages/IBM-5170-TECHREF 202.pdf)")
reset the keyboard ("[KBD_RESET](../../../../pubs/pc/reference/ibm/static/5170/techref/pages/IBM-5170-TECHREF 212.pdf)"),
For example, at one point, the BIOS ("[TEST.21](../../../../pubs/pc/reference/ibm/static/5170/techref/1984-03/pages/IBM-5170-TECHREF 202.pdf)")
reset the keyboard ("[KBD_RESET](../../../../pubs/pc/reference/ibm/static/5170/techref/1984-03/pages/IBM-5170-TECHREF 212.pdf)"),
which unmasked the keyboard IRQ and waited for an interrupt, using a loop where CX was initialized to zero and then
decremented until either CX wrapped around to zero again *or* an interrupt occurred. The "TEST.21" code then assumed
that if "KBD_RESET" returned zero in CX, no interrupt had occurred.