🇯🇵 Sharp MZ-80B: Part 2 (Keyboard Refurb Begins) [ скачать в хорошем качестве

🇯🇵 Sharp MZ-80B: Part 2 (Keyboard Refurb Begins) [

Whilst we wait for replacement parts for the motherboard, let's have a look at the keyboard and see what needs to be done there. Replacement parts needed are: Z80 CPU (ok) Z80 PIO (ordered) 8253 PIT (ordered) 8255 PPI (ordered) Two 2716 ROMs (ok) 6116 2KB SRAM (ok) It has three custom Gate Arrays that are irreplaceable ... they look okay ... ? I'm working on a replacement memory board to replace the 32 x 4116 DRAMs with two 62256 SRAMs, and an upgraded 16KB video RAM board. I'm also going to try to implement the "RAM Checker" mentioned in the Service Manual, so the boot ROM (IPL) will upgraded to a 2732 which can be switched between the original IPL and the RAM checker. Back to the keyboard ... I ended up completely stripping it so I could figure out the key matrix which I then duly drew up in KiCad. I also cleaned and re-sprayed the metal plate. All the details are on my Github: https://github.com/BrettHallen/Sharp-... It uses 12mm tactile switches with 7mm height for the function, cursor and cassette (CMT) controls. The keyboard uses Futuba MD-4P-CS key switches (I believe, black body with orange base) with MD-7 (? ... black body & base) for illuminated keys, and a different coloured MD-4 (white body, cream base) for the SPACE bar. I decided, as I'd figured out the key matrix, that I'd just replace the original keyboard PCB with my own replacement design, along with using new-old-stock (NOS) Futuba key switches (about US$1.50 each). This will take me a little bit of time to get right. 00:15 ... Motherboard progress 03:45 ... Initial keyboard checking 11:00 ... Desoldering with the ENGINEER SS-03 14:00 ... Removing the PCB 15:30 ... PCB and plate status 17:00 ... Tactile switch replacement 19:15 ... New plan: DIY replacement PCB 22:20 ... Channel thanks & outro -------------------------------- From Part 1: Finally got my hands on one of these all-in-one Japanese computers from the early 80s (1981) ... it just has a few, tiiiiiiny little problems ... 🥹 ... well, there's a bit of corrosion on the motherboard so requires a lot of chip replacement and cleaning. It currently doesn't boot. As it's a Japanese model it expects 100VAC so I will look at replacing this with a 240VAC supply - the PSU outputs ±5VDC and +12VDC. I am also looking at expanding it ... but let's see if I can get it working first. I understand that there were several main lines of Sharp MZ-branded computers: MZ-40K series: the original kit computer with Fujitsu's 4-bit MB8843 CPU MZ-80K series (mono text): MZ-80K, MZ-80C, MZ-80K2, MZ-80K2E, MZ-80A with Sharp's LH0080 (Z80) CPU MZ-700 series (MZ-80K with colour graphics): MZ-700, MZ-800, MZ-1500 MZ-80B series (see below) There was also the MZ-3500 series with dual Z80 CPUs, the MZ-5500/MZ-6500/MZ-8000 series with Intel CPUs and an MZ-100 laptop with an Intel 8088. The MZ-80B was a development of the MZ-80K kit computer, and was positioned as a business computer. The MZ-80B range includes: MZ-80B (this computer) MZ-80B2 (extra VRAM) MZ-2000 (higher resolution, optional colour) MZ-2200 (standalone machine, no monitor built-in) The MZ-80B has the following specifications: Z80 compatible CPU at 4MHz 320x200 monochrome graphics or 40x25/80x25 text 2KB boot ROM (Initial Program Loader or IPL) 2KB character generator ROM 32KB of RAM expandable to 64KB (MZ-80RM) 2KB of character RAM 8KB of graphics RAM expandable to 16KB (MZ-80GMK) It doesn't have BASIC built-in so it needs to be loaded from tape (or disk). It has two reset buttons ... a RESET that does a warm restart and an IPL reset that does a cold restart. The built-in tape drive is controlled by the IPL (no mechanical buttons) and you can add a floppy drive if you have the expansion boards. My machine does have the internal 32KB RAM upgrade but doesn't have the MZ-80EU Expansion Port required for installing expansion cards like: MZ-80IO2 Universal I/O Card MZ-80IO3 RS-232 Serial MZ-80IO4 IEEE/HPIB/GPIB MZ-80GMK Graphics RAM Expansion Card MZ-80FI Floppy Disk I/O Card MZ-80FB and MZ-80GBK Floppy Disk and Expansion Floppy Disk ROM card -------------------------------- Check out my Patreon for regular blog-type updates between videos - there is a free membership tier and two paid tiers (US$2 and US$5). There is also a one-week trial for the paid tiers so if you don't think it's worth it, then cancel ... no hard feelings ... I appreciate any support, even if it's just subscribing to my YouTube channel!   / thecluelessengineer   -------------------------------- Music by Karl Casey @ White Bat Audio https://karlcasey.bandcamp.com    / @whitebataudio