Macintosh-HW/macsehw
1
0
Fork 0
mirror of https://github.com/quorten/macsehw.git synced 2025-02-11 15:30:29 +00:00
Code Issues Projects Releases Wiki Activity

Work-in-progress improvements to BBU.

Browse Source
This commit is contained in:
Andrew Makousky 2021-04-23 20:30:16 -05:00
parent 7ef514a1eb
commit 5fc5d3489d
6 changed files with 170 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
firmware/adb/README.md
View File

@ -2,3 +2,24 @@
This directory contains the firmware for the ADB (Apple Desktop Bus)
chip, which is actually an Apple-branded PIC16CR54 microcontroller.
# Functioning of the ADB
See Guide to the Macintosh Family Hardware, page 312.
* Automatically polls the last device that has sent data, the _active
device_. Then shifts it out to the VIA, that causes an interrupt.
* A non-active device asserts a _Service Request_ signal to the ADB
when it has data to send. The ADB asserts an interrupt request
signal to the VIA, which sets bit 3 in data register 3 to 0.
Respond to requests of the ADB Manager to poll each device to find
which one asserted the Service Request.
Data bits are encoded as follows:
* Bit-cell time: 100 us
* 0: low 65 us
* 1: low 35 us

6
hardware/fpga/bbu/Makefile
View File

@ -12,8 +12,14 @@ all: $(TARGETS)
bbu.vvp: bbu.v common.vh
test_stdlogic.vvp: test_stdlogic.v stdlogic.v common.vh
test_mac128pal.vvp: test_mac128pal.v test_stdlogic.v stdlogic.v \
mac128pal.v common.vh
iverilog -Wanachronisms -Wimplicit -Wportbind -Wselect-range \
-Winfloop -Wsensitivity-entire-vector \
-Wsensitivity-entire-array \
-o $@ $<
./test_mac128pal.vvp -lxt
clean:
rm -f $(TARGETS)

1
hardware/fpga/bbu/docs/getsheets.sh
View File

@ -8,3 +8,4 @@ curl -L -o 'http://www.applelogic.org/files/Z8530UM.pdf'
curl -L -O 'http://archive.6502.org/datasheets/rockwell_r6522_via.pdf'
curl -L -O 'http://www.assmann-wsw.com/fileadmin/datasheets/ASS_0981_CO.pdf'
curl -L -O 'https://media.digikey.com/pdf/Data%20Sheets/Rohm%20PDFs/MSM51V17405F.pdf'
curl -L -O 'http://www.bitsavers.org/components/vti/databook/1986_VTI_Gate_Array_Design_Manual.pdf'

55
hardware/fpga/bbu/lfsr.c Normal file
View File

@ -0,0 +1,55 @@
/*
20210403/https://patentimages.storage.googleapis.com/52/04/e8/f5a5f0a7214a9c/US4910670.pdf
20210403/https://github.com/mamedev/mame/blob/master/src/mame/drivers/mac128.cpp#L486
20210403/https://en.wikipedia.org/wiki/Linear-feedback_shift_register
*/
#include <stdio.h>
#include <stdlib.h>
int
main(int argc, char *argv[])
{
unsigned int k = 1;
/* if (argc != 2)
return 1;
if (sreg == 0)
return 1; */
fputs(" 0, ", stdout);
while (k < 64) {
unsigned char sreg;
unsigned char preg;
unsigned char j;
unsigned int i = 0;
/* sreg = (char)atoi(argv[1]); */
sreg = k;
sreg &= 64 - 1;
/* N.B.: Careful, we do not check the exit condition at the start.
We must have a special hardware condition check to allow
shifting once before triggering the exit condition. As we also
do for the zero condition. */
do {
sreg = (sreg >> 1) |
((((sreg >> 0) ^ (sreg >> 1)) & 1) << 5);
sreg &= 64 - 1;
preg = sreg;
/* j = 6;
while (j > 0) {
j--;
putchar((preg & (1 << 5)) ? '1' : '0');
preg <<= 1;
}
putchar('\n'); */
i++;
} while (sreg != 0x20);
printf("%2d, ", i);
k++;
if ((k & (8 - 1)) == 0)
putchar('\n');
}
putchar('\n');
return 0;
}

108
hardware/fpga/bbu/mac128pal.v
View File

@ -53,12 +53,15 @@ module tsm(simclk, n_res,
output wire s0, dtack;
`power wire vcc;
reg qx;
// We must implement RESET for simulation or else this will never
// stabilize.
always @(negedge n_res) begin
// casl = 1; cash = 1; s0 = 1; dtack = 1;
ras <= 1; vclk <= 1; q2 <= 1; q1 <= 1;
qx <= 1;
end
// Simulate combinatorial logic.
@ -88,18 +91,30 @@ module tsm(simclk, n_res,
~(~pclk & q1 & s1 // video cycle
| ~pclk & q1 & ~ramen & dtack // processor cycle
| pclk & ~ras); // any other cycle
vclk <=
/* vclk <=
~(~q1 & pclk & q2 & vclk // divide by 8 (1MHz)
| ~vclk & q1
| ~vclk & ~pclk
| ~vclk & ~q2);
| ~vclk & ~q2); */
vclk <=
~(~sysclk // one-shot divide by 8 (1MHz)
| q1
| ~pclk
| ~qx
| ~q2);
q1 <=
~(~pclk & q1
| pclk & ~q1); // divide `pclk` by 2 (4MHz)
// TODO FIXME: Real PALs don't have this extra bit of memory!
qx <=
~(~q1 & ~pclk & qx // divide by 4 (2MHz)
| ~qx & q1
| ~qx & pclk);
q2 <=
~(~q1 & pclk & q2 // divide by 4 (2MHz)
~(~q1 & ~pclk & qx & q2 // divide by 8 (1MHz)
| ~q2 & q1
| ~q2 & ~pclk);
| ~q2 & pclk
| ~q2 & ~qx);
end
end
endmodule
@ -131,6 +146,9 @@ module lag(simclk, n_res,
snddma <= 1; reslin <= 1; resnyb <= 1;
end
// TODO FIXME: After converting to one-shot vclk, we have a few
// glitches still to fix up.
// Simulate registered logic.
always @(posedge sysclk) begin
if (n_res) begin
@ -232,6 +250,11 @@ the whole interplay works in detail.
regular visible area sweep before we de-assert *HSYNC, so actually
we won't be drawing these pixels during horizontal blanking.
Nevertheless, if you do need a signal that covers the whole active
pixel period, you can logically OR together *HSYNC and VIAPB6.
Make sure that you use buffering between the VIA and VIAPB6 to
prevent the CPU from driving the CRT haywire.
3. Now, the ultimate conclusion of the glitched counter. When we
wrap-around to zero, both *HSYNC and VIAPB6 are still asserted. We
check for this condition to generate resnyb in the middle of a
@ -393,21 +416,22 @@ module tsg(simclk, n_res,
// Simulate registered logic.
always @(posedge sysclk) begin
if (n_res) begin
// TODO VERIFY: q6 missing?
q6 <= ~(0);
q6 <= ~(~q3); // delayed copy of 1MHz q3 signal
clkscc <=
~(clkscc & ~pclk & ~q4
| clkscc & ~pclk & ~q3
| clkscc & ~pclk & vclk
| ~clkscc & pclk
| ~clkscc & q4 & q3 & ~vclk); // skip one inversion every 32 cycles
~(clkscc & pclk & ~q4
| clkscc & pclk & ~q6
| clkscc & pclk & q3
| ~clkscc & ~pclk
| ~clkscc & q4 & q6 & ~q3); // skip one inversion every 32 cycles
viacb1 <= ~(~keyclk); // buffer the keyboard clock
pclk <= ~(pclk); // divide SYSCLK by 2 (8MHz)
q3 <= ~(~vclk); // `sysclk` / 16
q3 <=
~(~q3 & ~vclk
| vclk & q3); // `sysclk` / 16
q4 <=
~(q4 & q3 & ~vclk // `sysclk` / 32
| ~q4 & ~q3 // } J for generating CLKSCC
| ~q4 & vclk);
~(q4 & q6 & ~q3 // `sysclk` / 32
| ~q4 & ~q6 // } J for generating CLKSCC
| ~q4 & q3);
end
end
endmodule
@ -431,7 +455,7 @@ module asg(simclk, n_res,
// We must implement RESET for simulation or else this will never
// stabilize.
always @(negedge n_res) begin
n_dmald <= 1;
n_dmald <= 1; pwm <= 1;
r5 <= 1; r4 <= 1; r3 <= 1; r2 <= 1; r1 <= 1; r0 <= 1;
end
@ -450,14 +474,52 @@ module asg(simclk, n_res,
// N.B.: This expansion almost exceeds the term limit of the
// PAL.
// * Load value on *DMALD.
// * If value is zero, set exit condition immediately.
// Otherwise, set "not exit" condition. This way we can
// load 0x20 and not immediately quit.
// * Regular loop, shift and check for exit condition on
// shifted condition. Okay, that's a bit ugly, but fine.
// It would be simpler to check for exit condition on
// stored value.
// ((a) ? ((b) ? d : e) : c);
// (a & ((b & c) | (~b & d))) | (~a & c);
// r0 <=
// ~(~a & ~c
// | ~a & ~c & b
// | ~a & ~c & ~e
// | ~b & a & ~e
// | ~b & a & ~e & ~c
// | ~b & ~c & ~a & ~c
// | ~b & ~c & ~e & a
// | ~b & ~c & ~e & ~c
// | ~d & a & b
// | ~d & a & b & ~c
// | ~d & a & ~e
// | ~d & a & ~e & ~c
// | ~d & ~c & ~a
// | ~d & ~c & b & a
// | ~d & ~c & b
// | ~d & ~c & ~e & a
// | ~d & ~c & ~e & ~c);
r0 <= (~n_dmald) ? rdq0 : ((pwm & vclk) ? r1 : r0);
// TODO FIXME: Not in PAL equation format.
r0 <= n_dmald & (r0 ^ ~pwm);
r1 <= n_dmald & (r1 ^ (r0 & ~pwm));
r2 <= n_dmald & (r2 ^ (r1 & r0 & ~pwm));
r3 <= n_dmald & (r3 ^ (r2 & r1 & r0 & ~pwm));
r4 <= n_dmald & (r4 ^ (r3 & r2 & r1 & r0 & ~pwm));
r5 <= n_dmald & (r5 ^ (r4 & r3 & r2 & r1 & r0 & ~pwm));
pwm <= n_dmald & r5 & r4 & r3 & r2 & r1 & r0;
r0 <= (~n_dmald) ? rdq0 : ((pwm & vclk) ? r1 : r0);
r1 <= (~n_dmald) ? rdq1 : ((pwm & vclk) ? r2 : r1);
r2 <= (~n_dmald) ? rdq2 : ((pwm & vclk) ? r3 : r2);
r3 <= (~n_dmald) ? rdq3 : ((pwm & vclk) ? r4 : r3);
r4 <= (~n_dmald) ? rdq4 : ((pwm & vclk) ? r5 : r4);
r5 <= (~n_dmald) ? rdq5 : ((pwm & vclk) ? (r0 ^ r1) : r5);
pwm <= (~n_dmald)
? ((~rdq5 & ~rdq4 & ~rdq3 & ~rdq2 & ~rdq1 & ~rdq0) ? 0 : 1)
: ((pwm & vclk)
? (((r0 ^ r1) & ~r5 & ~r4 & ~r3 & ~r2 & ~r1) ? 0 : 1)
: pwm);
end
end
endmodule

4
hardware/fpga/bbu/test_mac128pal.v
View File

@ -109,10 +109,10 @@ module test_mac128pal();
// Set simulation time limit.
initial begin
// #1920000 $finish;
#1920000 $finish;
// PLEASE NOTE: We must simulate LOTS of cycles in order to see
// what the oscilloscope trace for one video frame looks like.
#30720000 $finish;
// #30720000 $finish;
end
// We can use `$display()` for printf-style messages and implement