1. SWTP 6800 simulator usage¶

Date:: 2022-06-06
Revision:: $Format:%H$
Copyright:: See LICENSE.txt for terms of use.

Copyright notice

The following copyright notice applies to the SIMH source, binary, and documentation:

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Except as contained in this notice, the names of The Authors shall not be used in advertising or otherwise to promote the sale, use or other dealings in this Software without prior written authorization from the Authors.

This memorandum documents the SWTP 6800 simulator.

1.1. Simulator files¶

sim/: scp.h

sim_console.h

sim_defs.h

sim_fio.h

sim_rev.h

sim_sock.h

sim_tape.h

sim_timer.h

sim_tmxr.h

scp.c

sim_console.c

sim_fio.c

sim_sock.c

sim_tape.c

sim_timer.c

sim_tmxr.c
sim/swtp6800/common: bootrom.c – Boot ROM simulator

dc-4.c – Disk controller simulator

lfd-400.c – Disk controller simulator

i2716.c – 2716 ROM simulator D

m6800.c – M6800 CPU simulator

m6810.c – M6810 RAM simulator

mp-8m.c – 8K RAM board simulator

mp-a.c – MP-A CPU board simulator

mp-a2.c – MP-A2 CPU board simulator

mp-b2.c – MP-B2 Motherboard board simulator

mp-s.c – Serial port board simulator
sim/swtp6800/swtp6800: mp-a_sys.c – System definitions for MP-A CPU board

mp-a2_sys.c – System definitions for MP-A2 CPU board

swtp_defs.h – System definitions for the SWTP 6800

Additional files are:

sim/swtp6800/swtp6800: swtbug.bin – SWTBUG boot ROM code

swtp6800mp-a.ini – Initialization for MP-A CPU

swtp6800mp-a2.ini – Initialization for MP-A2 CPU

1.2. SWTP 6800 features¶

The SWTP 6800 simulator is configured as follows:

Device names(s)	Simulates
`m6800+`	MP-A CPU with
`m6810+`	128B of RAM and
`bootrom`	512 – 8192B of boot ROM
`m6800+`	MP-A2 CPU with
`m6810+`	128B of RAM
`bootrom+`	512 – 8192B of boot ROM
`i2716`	4 each 2716 EPROMS and external RAM above 40K
`Motherboard`	MP-B2 with 8 SS-30 plugs and 7 SS-50 plugs
`MP-8M`	6 each 8K byte memory board (`0-7FFFH` & `A000-DFFFH`)
`DC-4`	SS-30 5-¼″ dual floppy disk controller
`LFD-400`	SS-30 5-¼″ dual floppy disk controller
`MP-S`	SS-30 serial I/O port

The simulator builds as two executable files, SWTP6800MP-A and SWTP6800MP-A2, one for each of the processor boards available.

Most devices can be disabled or enabled, by the commands:

SET <dev> DISABLED
SET <dev> ENABLED

The SWTP 6800 simulator implements several unique stop conditions:

If an undefined instruction is decoded, a STOP_INST is set
If an undefined memory or I/O address is selected and MTRAP is enabled, a STOP_INST is set
If an undefined interrupt occurs and ITRAP is enabled, a STOP_INST is set

The LOAD command supports both S19 format and BIN format tapes. If the file extension is .S19, or the -h switch is specified with LOAD, the file is assumed to be S19 format; if the file extension is .BIN, or the -b switch is specified, the file is assumed to be BIN format.

1.2.1. Motherboard¶

The current simulator supports the MP-B2 motherboard. This board allows for inserting of the selected CPU, up to 6 MP-8M 8K byte memory boards, and one additional SS-50 board. It will allow the addition of up to 6 other SS-50 peripherals with the MP-S and DC-4.

Addresses are fixed for each of the 6 MP-8M boards as shown below:

Device	Base address
`bd0`	`0000H`
`bd1`	`2000H`
`bd2`	`4000H`
`bd3`	`6000H`
`bd4`	`0A000H`
`bd5`	`0C000H`

The simulator allows each board to be enabled or disabled individually to simulate the presence or absence of a particular board. This is the standard layout of memory in a SWTP 6800.

If the LFD-400 FDC is enabled, then the bd5 MP-8M must be disabled. The LFD-400 used CC00-CC0FH for its I/O address space.

1.2.2. MP-A CPU card¶

The simulator for the SWTP 6800 MP-A uses several files. The simulator is depicted in figure 1.

_images/swtp6800-mpa.svg — Figure 1. MP-A Simulator¶

The MP-A CPU has several available options.

1.2.2.1. BOOTROM device¶

The BOOTROM allows selection of the size of the ROM:

SET BOOTROM NONE              No Boot PROM
SET BOOTROM 2704              0.5K PROM
SET BOOTROM 2708              1K PROM
SET BOOTROM 2716              2K PROM
SET BOOTROM 2732              4K PROM
SET BOOTROM 2764              8K PROM

The BOOTROM device assigns the base of the ROM image to 0E000H of simulated memory.

The BOOTROM image file is attached to the BOOTROM device as follows:

ATTACH BOOTROM SWTBUG.BIN

1.2.2.2. CPU device¶

The CPU device allows setting the simulated behavior for interrupts and references to unimplemented memory.

SET CPU ITRAP                 Trap interrupts
SET CPU NOITRAP               Don't trap interrupts
SET CPU MTRAP                 Trap unimplemented memory
SET CPU NOMTRAP               Don't trap unimplemented memory
SET CPU HISTORY               Enable the collection of history

1.2.2.3. M6800 registers¶

The CPU registers include the visible state of the processor as well as the control registers for the interrupt system.

Name	Size	Comments
`PC`	16	Program counter
`SP`	16	Stack pointer
`A`	8	Accumulator A
`B`	8	Accumulator B
`IX`	16	Index register
`CCR`	8	Condition code register

The CPU display radix can be set for octal, decimal or hexadecimal. The commands are as follows:

SET CPU OCT
SET CPU DEC
SET CPU HEX

The current CPU display radix can be found with:

SHOW CPU RADIX

1.2.3. MP-A2 CPU card¶

The simulator for the SWTP 6800 MP-A uses several files. The simulator is depicted in figure 2.

_images/swtp6800-mpa2.svg — Figure 2. MP-A2 Simulator¶

The MP-A CPU has several available options.

1.2.3.1. BOOTROM device¶

The BOOTROM allows selection of the size of the ROM:

SET BOOTROM NONE              No Boot PROM
SET BOOTROM 2704              0.5K PROM
SET BOOTROM 2708              1K PROM
SET BOOTROM 2716              2K PROM
SET BOOTROM 2732              4K PROM
SET BOOTROM 2764              8K PROM

The BOOTROM device assigns the base of the ROM image to 0E000H of simulated memory.

The BOOTROM image file is attached to the BOOTROM device as follows:

ATTACH BOOTROM SWTBUG.BIN

1.2.3.2. I2716 device¶

The i2716 device provides 4 units to simulate the 4 2716 ROM positions on the MP-A2 CPU board. They are i27160 to i27163.

The i2716 ROM image file is attached to one of the i2716 devices as follows:

ATTACH I27160 FILE0.BIN

1.2.3.3. CPU device¶

The CPU device allows setting the simulated behavior for interrupts and references to unimplemented memory.

SET CPU ITRAP                 Trap interrupts
SET CPU NOITRAP               Don't trap interrupts
SET CPU MTRAP                 Trap unimplemented memory
SET CPU NOMTRAP               Don't trap unimplemented memory

1.2.3.4. M6800 registers¶

The CPU registers include the visible state of the processor as well as the control registers for the interrupt system.

Name	Size	Comments
`PC`	16	Program counter
`SP`	16	Stack pointer
`A`	8	Accumulator A
`B`	8	Accumulator B
`IX`	16	Index register
`CCR`	8	Condition code register

The CPU display radix can be set for octal, decimal or hexadecimal. The commands are as follows:

SET CPU OCT
SET CPU DEC
SET CPU HEX

The current CPU display radix can be found with:

SHOW CPU RADIX

1.2.4. Programmed I/O devices¶

1.2.4.1. MP-S serial I/O board¶

This driver simulates the MP-S serial I/O board for the console connection to the SWTP 6800. The console simulated is either an ANSI terminal or a Teletype Model 33 with paper tape reader and punch. The console functions work correctly but the paper tape functions do not. The simulator simulates the M6850 registers to the extent required to support the console.

Console mode can be set as follows:

SET MP-S ANSI
SET MP-S TTY

Current console status can be shown with the following command:

SHOW MP-S

The MP-S driver simulates the paper tape reader (PTR) and paper tape punch (PTP) devices. These devices need to be attached to files before use. If the file specified is not present, then a new file is created. The attach and detach commands are as follows:

ATTACH PTR TEST
ATTACH PTP TEST1
DETACH PTR
DETACH PTP

Current PTP and PTR status can be shown with the following commands:

SHOW PTP
SHOW PTR

1.2.4.2. DC-4 quad double-sided single-/double-density 5-¼″ floppy disk controller board¶

This driver simulates the DC-4 floppy disk controller board. Normally this board connects to a dual drive DSDD 5-¼″ floppy system. In this emulation, I have provided for 4 drives, the maximum the WD1797 can support and the emulated drive images are also increased in size to 1.44 MB. FLEX can handle this size drive with no problems.

The DC-4 simulator provides for four drive units. The units are DC-40 to DC-43. These devices need to be attached to files before use. If the file specified is not present, then a new file is created. The units can be attached and detached to files as follows:

ATTACH DC-40 BOOT.IMG
DETACH DC-43

Current DC-4 status can be displayed with the following command:

SHOW DC-4

1.2.4.3. LFD-400 quad single-density 5-¼″ floppy disk controller board¶

This driver simulates the LFD-400 floppy disk controller board. Normally this board connects to a dual drive SSSD 5-¼″ floppy system. In this emulation, I have provided for 4 drives, the maximum the WD1791 can support.

The LDF-400 simulator provides for four drive units. The units are LDF-4000 to LDF-4003. The LDF-400 needs to be enabled before use as follows:

SET LDS-400 ENABLE

These devices need to be attached to files before use. If the file specified is not present, then a new file is created. The units can be attached and detached to files as follows:

ATTACH LDF-4000 BOOT.IMG
DETACH LDS-4002