Search found 135 matches

by tzok
Sat Jul 13, 2019 9:25 pm
Forum: ROM UPGRADES
Topic: 520STFM - TOS upgrade confusion
Replies: 8
Views: 763

Re: 520STFM - TOS upgrade confusion

You may look for 27C1000 (NOT 010 nor 1001) EEPROMs, but they are likely to be 200ns ones, so on the very border line of the acceptable latency for a stock 8MHz ST. They are 32 pins, but the "excessive" pins can be tied together and hooked to VCC (except \OE which should be tied to GND). You may als...
by tzok
Wed Jun 26, 2019 8:51 pm
Forum: SOFTWARE PROGRAMMING & DISCUSSION
Topic: change a bit in a variable ?
Replies: 6
Views: 642

Re: change a bit in a variable ?

It's pretty common in C... Set bit 3 (0 based index, so bit 3 is 4th bit): a|=(1<<3) Clear bit 3: a&=~(1<<3) << - shift left | - bitwise OR & - bitwise AND ~ - bitwise NOT Unfortunately Spectrum BASIC doesn't have bitwise operators, it only has logical ones :( I'm unsure if in HiSoft BASIC it is any...
by tzok
Wed Jun 26, 2019 2:29 pm
Forum: CHAT FORUM
Topic: Floppy corrupted when used on ST and PC won't read it ?
Replies: 18
Views: 1115

Re: Floppy corrupted when used on ST and PC won't read it ?

So exactly opposite to my issue, but somehow expected - I was using a true DD drive in Atari and a DD formatted HD diskette together with a HD drive in PC. It is not as bad as with 5,25" disks, but HD drives dislike DD disks and opposite way around too. It works when formatted, saved and read in the...
by tzok
Tue Jun 25, 2019 11:12 pm
Forum: CHAT FORUM
Topic: Floppy corrupted when used on ST and PC won't read it ?
Replies: 18
Views: 1115

Re: Floppy corrupted when used on ST and PC won't read it ?

Was it a true DD floppy or a HD floppy formatted to 720kB? With the latter ones, I had the same problem.
by tzok
Sat Jun 15, 2019 9:55 pm
Forum: ROM UPGRADES
Topic: MASK AND ROM PINOUTS EXPLAINED
Replies: 2
Views: 1285

Re: MASK AND ROM PINOUTS EXPLAINED

Actually, there existed a 1Mbit non-JEDEC compatible EPROMs, which had the same A16 and /OE pin locations as MASK-ROMs, these were 27C1000 and 27C301. /CE pin location (22) is the same with all 27C1001/010/1000/301 and the MASK-ROM (you are showing pin numbers for 28 pin 256kb MASK-ROM)... or maybe ...
by tzok
Fri Jun 07, 2019 9:26 pm
Forum: HARDWARE ISSUES
Topic: Bad resistor?
Replies: 5
Views: 630

Re: Bad resistor?

These are not even resistors, but just a fancy jumper wires... apparently someone moved them from one position to another from the top (without removing the board from bottom case).
by tzok
Fri Jun 07, 2019 10:55 am
Forum: STFM
Topic: C070789-001 REV .D
Replies: 2
Views: 2627

Re: C070789-001 REV .D

Yet another C070789-001 REV .D:
C070789-001_REV.D.jpg
C070789-001_REV.D.jpg (544.11 KiB) Viewed 979 times
by tzok
Mon Jun 03, 2019 8:48 pm
Forum: HARDWARE DISCUSSIONS
Topic: Si5351A clock generator - any good for a booster?
Replies: 2
Views: 479

Si5351A clock generator - any good for a booster?

I have recently found a very interesting chip called Si5351A. It is a 3 channel clock generator (8kHz - 160MHz). All 3 clocks can be phase locked. Chip is programmable by the I2C bus. It is available as an breakout board from Adafruit, or from Aliexpress. Have anyone considered using it for an ST bo...
by tzok
Wed Mar 27, 2019 6:21 pm
Forum: PSU (power supplies)
Topic: 520ST PSU Remake
Replies: 45
Views: 3831

Re: 520ST PSU Remake

As far As I remember it needs +/-12V solely for UART (RS232/MIDI), and of course +12V also for floppy. Good thing is, a custom PSU may have two plugs - one for ST and one for SF floppy.
by tzok
Wed Mar 27, 2019 4:35 pm
Forum: PSU (power supplies)
Topic: 520ST PSU Remake
Replies: 45
Views: 3831

Re: 520ST PSU Remake

Good replacement is also an Astec AA21430 (it was used in CISCO 1800 series routers). Connector is a regular DIN-7F. Same cable fits also SF3x4 floppy drives (despite they use DIN-5 and don't have -12V line).

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