MAMEWorld Forums - Programming - Re: Help emulating the model1 comm board

After like reading through like 20 datasheets, some new details on the Comm Boards...

So far we got for my Model-1 Comm:
- 128k EEPROM (though less than 2kb are actually used)
- Z80 CPU (up to 4mhz, exact clock yet to be determined)

- MB89237A DMA-Controller (stated by the MB89395 datasheet)
- MB89374 "Data Link Controller"

- MB8464 SRAM 8K x 8 (most likely the "internal" ram of the board)

- MB8421 SRAM 2K x 8 \ Master-Slave setup
- MB8431 SRAM 2K x 8 / for 16 bit data

- several 74xx ICs as well as 3 PALs/GALs.

The MB89237A seems to support memory-to-memory transfers.
The whole comm board seems to run in "8086 mode".

As far as for the ROMs, the Z80 code seems to be pretty straightforward

Code:


...

Sub Routine at 0x0000

SP = A000
DI
IM 0
jump 0x03A2

...

Sub Routine at 0x03A2

CALL 0x0403
CALL 0x0456
CALL 0x043B
CALL 0x0403

A = [C001]
DEC A
if zero jump 0x03C5

XOR A

OUT 40 = A

DI

CALL 065A
CALL 0460
CALL 03E7
JP 0841

CALL 05B9
CALL 0460
CALL 05AA
CALL 03D4
JP 0757

A = 96
[8001] = A
CALL 07BA
(and so on...)

...

Sub Routine at 0x0403
A = 0x05
[C000] = A

CALL 0x0586

CALL 0x0590

XOR A
OUT 60 = A
OUT 40 = A

[800E] = A
[8006] = A
[8007] = A

A = 2
[8003] = A

A = [C0001]
OR A
if zero jump 0x0432

DEC A
if zero jump 0x043A (which is a RET)

A = 1
[8006] = A

RET

...

Sub Routine at 0x0432

A = 1
[8007] = A
[C004] = A
RET

...

Sub Routine at 0x044E
( reads basic dlc config from ROM, writes to DLC regs )

while not zero
 c = (hl)
 inc hl
 outi

RET

(
IOW	0B17	C7	- Mask register		- all enabled
	0A0E	00	- TX IRQ enable		- all disabled
	090D	09	- transmit control	- txrst txlast
	080B	00	- RX IRQ enable		- all disabled
	070A	03	- receive controll	- HUNT STC
	061A	03	- BRG1 divide		- DIV0 DIV1
	0519	00	- BRG1/DPLL controll	- all disabled
	0400	02	- protocol select	- PS1
	0301	0C	- crc select		- CRCM1 CRCM0
	0202	21	- transfer mode		- CODE1 TCX0
	0114	02	- transmit mode		- TXUEND
	0007	00	- modem controll	- all disabled
)
...

Sub Routine at 0x0586

IOR	050C		- transmit status

IOW	600C	60	- transmit status	- all disabled BUT two unused bits

while not zero
 IOR	6008/0008	- receive status 0
 IOR	000F		- serial data

HL = 011E
B = C

CALL 044E

RET
...

Sub Routine at 0x06FA

while bit 4 not set
 IOR	000C		- transmit status	- Z80 loops until bit 4 is set (0x04 - TXEND)

IOR	0009		- receive status 1
IOR	0008		- receive status 0

while bit0 set (RXRDY)
 IOR	000F		- serial data

IOW	0017	FF	- Mask register		- all enabled

IOR	0028		- most likely NOT the DLC

RET

...

I do all that stuff even without a Joystick

Soft-15kHz, cabMAME, For Amusement Only e.V.