Search found 21 matches

by tzok
Mon Jul 16, 2018 8:08 pm
Forum: HARDWARE DISCUSSIONS
Topic: My latest restoration in pictures
Replies: 13
Views: 370

Re: My latest restoration in pictures

I'd rather compare it to replacing old but still working bulbs with a modern ones. My opinion is to not replace anything that still works good. Caps in ST are not known to cause problems or being excessively faulty. There were a series of faulty caps in other home computers from '80s and '90s, but n...
by tzok
Mon Jul 16, 2018 7:39 pm
Forum: RTC (Real time clock)
Topic: no-software internal RTC
Replies: 20
Views: 1010

Re: no-software internal RTC

I haven't talked with Jookie, but for now, I think I know everything I need to know. The only unknown is how will TOS react on a year value of 0xB8, which fits the scheme but the real IKBD would never return it.
by tzok
Mon Jul 16, 2018 6:52 pm
Forum: RTC (Real time clock)
Topic: no-software internal RTC
Replies: 20
Views: 1010

Re: no-software internal RTC

I've done some research. Keyboard communicates with ST using a simple async serial protocol with baud rate of 7812 bps. Single bytes are being sent one by one with a pause of 4.5ms between each. Setting a clock is done by sending 0x1B followed by YY MM DD hh mm ss. Date is sent as hex, so for month ...
by tzok
Fri Jul 13, 2018 2:51 pm
Forum: HARDWARE DISCUSSIONS
Topic: When is a ST not a ST anymore ?
Replies: 52
Views: 1945

Re: When is a ST not a ST anymore ?

In most cases reverse engineering gives more or less incomplete emulation. FPGAs run a VHDL code, potentially it could be very close to the original design, but we'd have to have original chip production documentation to fully implement it in VHDL. For example - STf and STe had a joystick port contr...
by tzok
Fri Jul 13, 2018 1:07 pm
Forum: HARDWARE DISCUSSIONS
Topic: When is a ST not a ST anymore ?
Replies: 52
Views: 1945

Re: When is a ST not a ST anymore ?

What is the difference between emulating a whole computer in one FPGA chip and emulating most of the crucial chips in a separate FPGAs... for me it is still only an emulation. So cycle accurate copies of original chips in form of ASICs is ok, FPGA emulation is only emulation.
by tzok
Fri Jul 13, 2018 12:47 pm
Forum: HARDWARE DISCUSSIONS
Topic: Just got a crazy idea 'bulb'
Replies: 9
Views: 298

Re: Just got a crazy idea 'bulb'

So you'd need to have two 1Mbit SRAM chips, an MCU and the I2C Flash. The MCU would load an TOS image from Flash to SRAM during the reset phase (it should control the reset line to be able to keep it active until copying is done). You may use 2Mbit SRAM and a bank switching, but after some thinking ...
by tzok
Fri Jul 13, 2018 12:27 pm
Forum: HARDWARE DISCUSSIONS
Topic: My latest restoration in pictures
Replies: 13
Views: 370

Re: My latest restoration in pictures

Nice restoration, but IMHO cables for RAM mod should be of equal length and best point to connect them is in the middle of RAM chips (between U30 and U32). I also find recapping working units pointless. All caps I ever removed from working STs were in perfect shape (in terms of capacitance, ESR, and...
by tzok
Fri Jul 13, 2018 12:21 pm
Forum: HARDWARE ISSUES
Topic: Write protect on floppy ?!
Replies: 6
Views: 368

Re: Write protect on floppy ?!

I had similar issue, but I wasn't probing anything, just cleaned the WP switch on the floppy - it helped. I no longer use the floppy, but decided to keep it in its original place.
by tzok
Fri Jul 13, 2018 11:33 am
Forum: TWEAKS & FIXES
Topic: Motherboard capacitors - which to replace?
Replies: 7
Views: 524

Re: Motherboard capacitors - which to replace?

I have recapped a few STs and never found a faulty capacitor on its motherboard. Only one have slightly corroded aluminum cup, but still was well in specs according to the capacity, ESR and leakage. If they are sealed well (and apparently they are) and not put to excessive heat, they should be ok fo...
by tzok
Tue Mar 13, 2018 6:38 pm
Forum: HARDWARE ESSENTIALS
Topic: Source for DIN-14 and DB-19 connectors?
Replies: 1
Views: 235

Source for DIN-14 and DB-19 connectors?

Do you have any reliable source for DB-19 (ACSI) and DIN-14 (FDD) plugs, which ships worldwide?