Search found 433 matches

by marcelk
24 Jan 2020, 06:56
Forum: Hardware and software hacking
Topic: Gigatron optimisation for a lite version?
Replies: 7
Views: 113

Re: Gigatron optimisation for a lite version?

One advantage of the ROM is the ability to add custom and specialized functions though. This can be an appealing option, but you are not going to eliminate chips to gain this advantage. Probably not. We also tried the Z80 approach but indeed it didn't save any chips. It only made it harder to under...
by marcelk
23 Jan 2020, 22:36
Forum: Hardware and software hacking
Topic: Gigatron optimisation for a lite version?
Replies: 7
Views: 113

Re: Gigatron optimisation for a lite version?

The idea comes up frequently enough that it is the Gigatron FAQ :-). In the 1970s, very big ROMs were either slow, and large arrays of fast small ones completely out of place. Large capacity and fast-enough ROMs that can take over an 8-bit ALU function or some other complex logic only came about in ...
by marcelk
22 Jan 2020, 21:25
Forum: Hardware and software hacking
Topic: GTOS
Replies: 3
Views: 280

Re: GTOS

for the SDC, it first gave a Vol.ID FFFF FAILED , and after some partitioning and formatting it errored out with Vol.ID 0000 FAILED ; Maybe it is related to the alignment of the partition? The one that worked had the LBA flag on and its first sector was at 2048. I'm testing with a 128K system. It m...
by marcelk
22 Jan 2020, 18:02
Forum: Hardware and software hacking
Topic: GTOS
Replies: 3
Views: 280

Re: GTOS

There is an interesting thing going on with the sequence for entering SPI mode on these devices: for some SD cards CMD0 seems to send its reply without driving the bus in both directions: as if those cards still only have a weak pull-up (or none) on the MISO line during that response. Our pull-down ...
by marcelk
22 Jan 2020, 07:34
Forum: Hardware and software hacking
Topic: Pluggable control unit
Replies: 1
Views: 52

Re: Pluggable control unit

That's a cool idea! HG has proposed a modified instruction set for his chess program. A cartridge would be neat.
by marcelk
21 Jan 2020, 19:59
Forum: Kit assembly gallery
Topic: Half a night of soldering later...
Replies: 5
Views: 102

Re: Half a night of soldering later...

ferdy wrote:
21 Jan 2020, 17:50
it took me from 11PM to 4AM in the morning
That reminds me of constructing the breadboard version of what later became the Gigatron (except that there were several such nights over the course of almost two months :D). That was just three years ago now, but seems so far in the past now.
by marcelk
19 Jan 2020, 22:19
Forum: Hardware and software hacking
Topic: I guess I just build a...screensaver?
Replies: 9
Views: 340

Re: I guess I just build a...screensaver?

As it is now, the clock is 2 seconds off from the start. Just a small detail ;) In the example code, I mitigate this delay by fetching the frame counter immediately following the input: 10 input H,M,S:B=peek(14) This way, the mismatch is reduced to the time it takes for parsing the last user input ...
by marcelk
18 Jan 2020, 20:36
Forum: Hardware and software hacking
Topic: Opcode mods
Replies: 9
Views: 374

Re: Opcode mods

Thanks for clarifying. The only point I tried to make is that if you want to create extra output signals, every flip-flop's output on the board is exposed (as "bare metal you can solder to") and available for tapping into. None are hidden behind a buffer for example, as in many other designs. Theref...
by marcelk
15 Jan 2020, 20:17
Forum: Hardware and software hacking
Topic: Expansion bus
Replies: 87
Views: 10280

Re: Expansion bus

[*]don't use the ICSP header since SS is tied to reset and will crash/freeze the Gigatron How does this issue occur? /SS is an output, and should always be driven by the host aka Gigatron. So I don't follow this exactly, and wonder if you have a schematic of what that ICSP header exactly does on th...
by marcelk
09 Jan 2020, 12:09
Forum: Hardware and software hacking
Topic: And I so promised myself... (continued)
Replies: 4
Views: 231

Re: And I so promised myself... (continued)

Pin handling in BabelFish is localised in low-level functions, or at least it's pretty idiomatic when not. So porting BabelFish shouldn't be too hard. There is a RPi version in Contrib/xxxbxxx/, so it has been done before...