Search found 15 matches

by klf
18 Nov 2021, 15:01
Forum: Hardware and software hacking
Topic: Can I build with HC rather than HCT series ICs ?
Replies: 5
Views: 228

Re: Can I build with HC rather than HCT series ICs ?

My Gigatron is a wild mixture of LS, HC and HCT, whatever was available.

You have to keep in mind that HCT can be driven by LS, HC and HCT, but HC can only be driven by HC and HCT but not LS. The logic high output level of LS is too low for HC.
by klf
23 Oct 2021, 23:24
Forum: Hardware and software hacking
Topic: Gigatron OS - Some progress and a (solved) hardware mystery.
Replies: 23
Views: 6715

Re: Gigatron OS - Some progress and a (solved) hardware mystery.

It is true that PALs were common these times, but the Gigatron was designed as a TTL-only system. It even has diode matrix decoders. If Marcel and Walter had used GALs from the beginning, ALU and control logic would be significantly smaller. The whole system would fit onto an eurocard. But that was ...
by klf
23 Oct 2021, 19:28
Forum: Hardware and software hacking
Topic: Gigatron OS - Some progress and a (solved) hardware mystery.
Replies: 23
Views: 6715

Re: Gigatron OS - Some progress and a (solved) hardware mystery.

Did I understand correctly -- your Gigatron OS does not use the zeropage switching, so that it also works with the classic expansion board?

I want to keep my Gigatron GAL-free as long as possible :-)
by klf
22 Aug 2021, 17:11
Forum: Hardware and software hacking
Topic: Gigatron vs. Arduino Uno
Replies: 5
Views: 1484

Re: Gigatron vs. Arduino Uno

When I connect my software (or any other terminal software) through the (usb)serial to the Uno board I receive some weird chars (i.e.: "p°W8(ÓñS[¹$ß¡‹™[u"). If I send any ASCII char to the Arduino, the X1 red LED blinks but nothing happens. First get the serial communication working. Unti...
by klf
10 May 2021, 11:35
Forum: Hardware and software hacking
Topic: Possible ways of speeding up the Gigatron
Replies: 32
Views: 4906

Re: Possible ways of speeding up the Gigatron

The Gigatron was designed as a "TTL Microcomputer". Now there are some expansion ideas based on GALs. If you accept programmable logic in your highspeed Gigatron this could significantly shorten the critical path.
by klf
21 Nov 2020, 17:35
Forum: Kit assembly gallery
Topic: My Gigatron! It very almost works! (Help!)
Replies: 7
Views: 3520

Re: My Gigatron! It very almost works! (Help!)

Instead of feeding the shift register you could also add a parallel input to your Gigatron. Use a 74HCT574 or 374 octal flipflop and connect its outputs to BUS0..7. Clock (pin 11) goes to SER_LATCH (/VSYNC). Cut the /IE signal where it enters U39/74HCT595 at pin 13 and insert a three-pin jumper here...
by klf
21 Aug 2020, 16:09
Forum: Hardware and software hacking
Topic: microtron
Replies: 42
Views: 16587

Re: microtron

Up only: 74xx461, 463, 590, 591, 592, 593
Up and down: 74xx469, 579, 869, 867

74HC(T)590 should be the most common one.
by klf
20 Aug 2020, 17:25
Forum: Hardware and software hacking
Topic: microtron
Replies: 42
Views: 16587

Re: microtron

74HC393 is a ripple counter, like the 4040. Better use a 74HC163.
by klf
20 Aug 2020, 14:56
Forum: Escape Meta Alt Control Shift
Topic: Anyone got one for sale?
Replies: 3
Views: 3900

Re: Anyone got one for sale?

There is a Dutch company selling kits: https://www.budgetronics.eu/en/building ... a-25779-20
by klf
17 Aug 2020, 21:44
Forum: Hardware and software hacking
Topic: Ye Olde Gigatron and Gigatronski
Replies: 11
Views: 4533

Re: Ye Olde Gigatron and Gigatronski

Neither works.. The scope shows that it is oscillating, but the output voltage is very low. The propagation delay of these is about the same as the 74C04 according to the specification, but I doubt that would be the problem, as I see it oscillating nicely. Did you try to change the bias resistor? E...