Altair8800: New Simulator

This is the initial release of the Altair8800 simulator.

Why another Altair simulator? AltairZ80 has been described as a
“software simulator”, where the intent is to run software designed
specifically for executing under a simulator. Altair8800 is intended
to accurately simulate the Altair hardware and execute software
that will run unchanged on real hardware. Software and disk images
can be moved between the Altair8800 simulator and real Altair and
other S-100 hardware without any changes. The Altair8800 simulator
is a tool that can assist with the restoration of vintage Altair
and other S-100 hardware and software along with the development
of new hardware and software. The accomplish this, the following
are major differences between AltairZ80 and Altair8800.

* The monolithic design where devices access other devices directly
through external variables and functions is no longer supported.
All devices exchange data through a new BUS device. Memory and I/O
address decoding and transfers are now handled by the BUS device.
All interrupt requests are handled by the BUS device.

* System RAM was moved from the CPU device to a new RAM device and
managed by the BUS device.

* Banked RAM was moved from the CPU device to a new BRAM device.

* Banked RAM can only be accessed through the BUS device. Memory in
banks that are not currently selected cannot be accessed. The AZ80
“banked” RAM was removed.

* ROMs were moved from the CPU and DSK devices to the new ROM device.
Mike Douglas’ Altmon Monitor is also available through the ROM
device. The custom AltairZ80 ALTAIRROM, which is not compatible
with original Altair disk images, is also available.

* The custom ALTAIRROM boot loader was replaced with the original
MITS Disk Boot Loader as the default ROM.

* The monolithic Multiple-CPU/RAM/ROM/IO/BankedRAM CPU device has
been replaced with a generic CPU device that provides an abstraction
layer between SIMH and the supported CPU architectures (currently
8080 and Z80). All IO is handled through the BUS device. RAM, Banked
RAM, and ROM are each handled by their own independent devices.

* The AltairZ80 SIO device was replaced with the M2SIO0 and M2SIO1
devices. The M2SIO devices fully support TMXR.

* A new SIO device was added to provide generic, programmable, Serial
IO. TMXR is not supported on this device.

* The Altair 8800 did not have PTR or PTP hardware devices. They have
been removed and replaced with the M2SIO1 device. PTR and PTP devices
are defined by software executing on the simulator.

* Contention between multiple enabled serial devices checking the
single host keyboard for input is now handled by the BUS device.
Port 0xFF sense switches was moved to a new SSW device and IMSAI
programmed output was moved to a new PO device.

* The SIMH pseudo device no longer uses the removed PTR and PTP
devices. The SIMH device has its own IO system. To avoid conflicts
with other devices and remain compatible with the R and W utilities
written for AltairZ80, SIMH “borrows” I/O ports 12H and 13H during
file transfers. Only SIMH commands needed to support R and W file
transfers are supported. All other SIMH commands were removed.

* AltairZ80-specific versions of CP/M are not supported by Altair8800.

* PC queue was removed from CPU device and replaced with CPU HISTORY.

* The Altair8800 simulator only supports 16-bit address and 8-bit
data buses. 8086 and 68K CPU architectures were removed.

* All CPU timing (clockFrequency) and “sleeps” (SIO SLEEP) have been
removed. SIMH THROTTLE is fully supported and is the recommended
way to manage simulator speed and host CPU utilization. Executing
“SET THROTTLE 100K/1”, for example, should provide ample speed
without tasking the host CPU.

* HEXLOAD and HEXSAVE commands were added. The LOAD “-h” option has
been removed. Intel Hex and sRecord (coming soon) formats are
supported.

* The WD179X device was converted to an API.

* A new DSK API was added to provide a consistent way to manage soft
sector raw disk images.

* Support for the proprietary IMD disk image format was removed. Only
RAW disk images are supported.

The following devices are supported by this initial release:

BUS - Altair (S-100) Bus
CPU - Intel 8080 / Zilog Z80
RAM - 64K RAM
ROM - ROMs
BRAM - Banked RAM
DSK - MITS 88-DCDD Floppy Disk Controller
M2SIO0 - MITS 88-2SIO Port 0
M2SIO1 - MITS 88-2SIO Port 1
SSW - Sense Switches
PO - Programmed Output
SIO - Generic Serial I/O
SBC200 - SD Systems SBC-200
TARBELL - Tarbell SD and DD Floppy Disk Controller
VFII - SD Systems VersaFloppy II
SIMH - SIMH Pseudo Device

makefile

@@ -216,6 +216,10 @@ ifneq (3,${SIM_MAJOR})
   ifneq (,$(or $(findstring pdp6,${MAKECMDGOALS}),$(findstring pdp10-ka,${MAKECMDGOALS}),$(findstring pdp10-ki,${MAKECMDGOALS})))
     VIDEO_USEFUL = true
   endif
+  # building the Altair8800 could use video support
+  ifneq (,$(findstring altair8800,${MAKECMDGOALS}))
+    VIDEO_USEFUL = true
+  endif
   # building the AltairZ80 could use video support
   ifneq (,$(findstring altairz80,${MAKECMDGOALS}))
     VIDEO_USEFUL = true
@@ -2218,6 +2222,29 @@ ALTAIR = ${ALTAIRD}/altair_sio.c ${ALTAIRD}/altair_cpu.c ${ALTAIRD}/altair_dsk.c
 ALTAIR_OPT = -I ${ALTAIRD}
 
 
+ALTAIR8800D = ${SIMHD}/Altair8800
+ALTAIR8800 = \
+    ${ALTAIR8800D}/altair8800_sys.c \
+    ${ALTAIR8800D}/altair8800_dsk.c \
+    ${ALTAIR8800D}/s100_bus.c \
+    ${ALTAIR8800D}/s100_bram.c \
+    ${ALTAIR8800D}/s100_cpu.c \
+    ${ALTAIR8800D}/s100_po.c \
+    ${ALTAIR8800D}/s100_simh.c \
+    ${ALTAIR8800D}/s100_sio.c \
+    ${ALTAIR8800D}/s100_ssw.c \
+    ${ALTAIR8800D}/s100_ram.c \
+    ${ALTAIR8800D}/s100_rom.c \
+    ${ALTAIR8800D}/s100_z80.c \
+    ${ALTAIR8800D}/mits_2sio.c \
+    ${ALTAIR8800D}/mits_dsk.c \
+    ${ALTAIR8800D}/sds_sbc200.c \
+    ${ALTAIR8800D}/sds_vfii.c \
+    ${ALTAIR8800D}/tarbell_fdc.c \
+    ${ALTAIR8800D}/wd_17xx.c
+ALTAIR8800_OPT = $(ALTAIR8800_GCC_OPT) -I ${ALTAIR8800D} -DUSE_SIM_VIDEO ${VIDEO_CCDEFS}
+
+
 ALTAIRZ80D = ${SIMHD}/AltairZ80
 ALTAIRZ80 = ${ALTAIRZ80D}/altairz80_cpu.c ${ALTAIRZ80D}/altairz80_cpu_nommu.c \
 	${ALTAIRZ80D}/s100_dazzler.c \
@@ -2540,8 +2567,8 @@ ALL = pdp1 pdp4 pdp7 pdp8 pdp9 pdp15 pdp11 pdp10 \
 	microvax2000 infoserver100 infoserver150vxt microvax3100 microvax3100e \
 	vaxstation3100m30 vaxstation3100m38 vaxstation3100m76 vaxstation4000m60 \
 	microvax3100m80 vaxstation4000vlc infoserver1000 \
-	nd100 nova eclipse hp2100 hp3000 i1401 i1620 s3 altair altairz80 gri \
-	i7094 ibm1130 id16 id32 sds lgp h316 cdc1700 \
+	nd100 nova eclipse hp2100 hp3000 i1401 i1620 s3 altair altair8800 \
+	altairz80 gri i7094 ibm1130 id16 id32 sds lgp h316 cdc1700 \
 	swtp6800mp-a swtp6800mp-a2 tx-0 ssem b5500 intel-mds \
 	scelbi 3b2 3b2-700 i701 i704 i7010 i7070 i7080 i7090 \
 	sigma uc15 pdp10-ka pdp10-ki pdp10-kl pdp10-ks pdp6 i650 \
@@ -2869,6 +2896,12 @@ $(BIN)altair$(EXE) : ${ALTAIR} ${SIM}
 	$(MAKEIT) OPTS="$(ALTAIR_OPT)"
 
 
+altair8800 : $(BIN)altair8800$(EXE)
+
+$(BIN)altair8800$(EXE) : ${ALTAIR8800} ${SIM}
+	$(MAKEIT) OPTS="$(ALTAIR8800_OPT)"
+
+
 altairz80 : $(BIN)altairz80$(EXE)
 
 $(BIN)altairz80$(EXE) : ${ALTAIRZ80} ${SIM}