Change test for -e (exists) instead of -d (directory) so that the .git
entry is detected correctly and git version stamp logic runs as in any
other git repo. The .git entry is a file when the repo is a submodules
and possibly other obscure cases like multiple worktrees.
fixes#988
* Properly handle the case when a disk is not attached.
* Add register access for debugging.
* Assert DRQ as well as IRQ for software that checks DRQ.
* Add API to get the number of heads for the currently-selected
disk.
* Follow SIMH conventions for debug logging.
* Add ability to debug IMD from the wd179x debug settings.
Tests:
* Format and disk access on Cromemco CP/M 2.2, CDOS, 86-DOS,
MS-DOS 1.25, OASIS 5.6.
The ImageDisk sectsize field was incorrectly set to the number of
bytes in the sector, when it should be an index as follows:
00 = 128 bytes/sector
01 = 256 bytes/sector
02 = 512 bytes/sector
03 = 1024 bytes/sector
04 = 2048 bytes/sector
05 = 4096 bytes/sector
06 = 8192 bytes/sector
Tested disk formatting on MS-DOS 1.25, Cromemco CP/M 2.2,
Cromemco CDOS, OASIS 5.6.
The AB Digital Design B810 RAM card is a 256K Dynamic RAM card
with onboard refresh logic. AltairZ80 support emulates four of
these cards for a total of 16 banks.
As used for the OASIS operating system, the B810 is configured
with common memory at the low addresses (0000h-3FFFh) with 16
banks of 48K from 4000h-FFFFh.
In order to have the common memory appear from 0000-3FFFh, set
the COMMONLOW register to 1:
D COMMONLOW 1
Custom TTL design by Marvin Minsky. There are two displays: one
raster scan for bitmapped characters, and another random scan for
vector graphics. There is also a keyboard, and a UART for talking
to a host computer.
The computer is normally booted off a ROM which reads and starts a
secondary loader from the UART. The loader is responsible for reading
the payload, which comes in checksummed blocks. The LOAD command
accepts files in same format.
Previously, the RUN command would gather and set the desired
PC start address, but then it would invoke the reset logic for all
DEVICEs. The CPU DEVICE's reset routine might reasonably
initialize the PC to a known state which would the overwrite
the PC specified on the RUN command. This change performs
the reset before setting the PC to the specified value (or it's
previous value if no PC was supplied on the RUN command).
SSV ("Scroll Saver") was the Imlac console program and terminal
emulator at MIT's Dynamic Modeling group. It was written mainly by
P. David Lebling. This copy is from Purdue University, courtesy of
Tom Uban. SSV is required to run Maze; the game expects to find SSV's
font data in core.
