Search found 647 matches
- 26 Apr 2023, 23:17
- Forum: Hardware and software hacking
- Topic: ROM switching:
- Replies: 12
- Views: 4965
Re: ROM switching:
You'll probably get away with no de-bouncing, but it is poor design practice; you'll be resetting the 161's multiple times, at the mercy of whatever switch you decide to use.
- 26 Apr 2023, 16:08
- Forum: Hardware and software hacking
- Topic: ROM switching:
- Replies: 12
- Views: 4965
Re: ROM switching:
When switching ROM's, unless the current native code path is the same, (between the previous ROM and the new ROM), the Gigatron will most certainly have timing issues and/or most likely crash.
You will need some sort of reset to initialise the PC to 0x0000.
You will need some sort of reset to initialise the PC to 0x0000.
- 25 Apr 2023, 17:51
- Forum: Hardware and software hacking
- Topic: ROM switching:
- Replies: 12
- Views: 4965
Re: ROM switching:
I was looking for a way to add an external reset to the Gigatron without having to change the hardware on the motherboard. This does not seem to be possible. The MCP100 has a push-pull output. It's only one trace you have to cut and then insert your circuit; even if you use the device bmwtcu pointe...
- 24 Apr 2023, 21:45
- Forum: Hardware and software hacking
- Topic: ROM switching:
- Replies: 12
- Views: 4965
Re: ROM switching:
Here is some more information on the original design that got lost in a different thread: Other vintage computers use writing to address 0x0, 0x1, 0x2, 0x3 to switch the bank ... For 32 and 64 kb, it's very simple: one or two D flip-flops that are set to 1 or 0 by writing to the address 0 or 1 (2 an...
- 24 Apr 2023, 21:22
- Forum: Hardware and software hacking
- Topic: ROM switching:
- Replies: 12
- Views: 4965
Re: ROM switching:
If you look at the schematic in the Gigatron manual, page 48, you'll see the MCP100 with a !RST output, then on page 49 you'll see the !RST output fed to the four 161's !MR input, (the program counter). All I did was add a de-bounced reset switch to the MCP100; when switching ROM's, (my ROM switcher...
- 24 Apr 2023, 14:03
- Forum: Hardware and software hacking
- Topic: gtBASIC
- Replies: 435
- Views: 123832
Re: gtBASIC
Can you point me to an explanation of this code: ' Defines the amount of contiguous RAM needed for blit stripes, (in this case 15*6 + 1), min address and search direction _blitStripeChunks_ 15, &h1FA0, &hFFFF, ascending Marcel's original sprite routine, (that I call a blit), is only capable...
- 23 Apr 2023, 12:29
- Forum: Hardware and software hacking
- Topic: Draw lines [tests]
- Replies: 4
- Views: 1045
Re: Draw lines [tests]
Yeah, that's better, no more timing issues and definitely noticeably faster as well, also runs fine on my new version of ROMvX0.
- 23 Apr 2023, 12:26
- Forum: Escape Meta Alt Control Shift
- Topic: 1-byte NOP for vCPU
- Replies: 3
- Views: 2568
Re: 1-byte NOP for vCPU
Makes sense, unfortunately there is no vCPU NOP single byte instruction, you could do funky stuff with RET, PUSH or POP if you kept track of the stack/return address state, but that would probably be extremely inefficient in the long run. https://github.com/kervinck/gigatron-rom/blob/master/Docs/vCP...
- 23 Apr 2023, 09:17
- Forum: Escape Meta Alt Control Shift
- Topic: 1-byte NOP for vCPU
- Replies: 3
- Views: 2568
Re: 1-byte NOP for vCPU
All the one byte instructions modify vAC or the stack, I assume this is not good enough? What do you need a NOP for? 1) Alignment of data? 2) Padding of data? 3) Alignment of code so that you can stitch two unrelated code segments together? 1) and 2) are not an issue on the Gigatron, 3) there is a b...
- 23 Apr 2023, 00:00
- Forum: Hardware and software hacking
- Topic: Draw lines [tests]
- Replies: 4
- Views: 1045
Re: Draw lines [tests]
In my emulator, timing errors are reported at the end of each sweep for both versions. Also version 2 try's to write to address 0.