Search found 69 matches

by S_U_C
Mon Feb 21, 2022 4:56 pm
Forum: Hardware
Topic: Correct tape type
Replies: 12
Views: 6298

Re: Correct tape type

If other tapes work then it must be the tape/tape cassette.
There should be a spring loaded pad behind the tape to hold the tape close to the tape head.
It is possible that the cassettes alingment holes are slightly out place. These and the pad present the tape to the tape head
by S_U_C
Mon Feb 21, 2022 12:28 pm
Forum: Hardware
Topic: Correct tape type
Replies: 12
Views: 6298

Re: Correct tape type

Hi,
Ferric type 1 is OK.
Is it a branded tape like TDK?
Or just a cheap "data" tape?
Weak recordings, low sound, may indicate that the tape head requires a clean.
by S_U_C
Sun Jan 02, 2022 11:37 am
Forum: Hardware
Topic: SFD-700/800 .dsk Disk analyse
Replies: 2
Views: 2033

Re: SFD-700/800 .dsk Disk analyse

Hi, the IPLPRO tags are to indicate that a disk is bootable i.e. a system disk. It contains a short sys-name, size, load , exec address and the start position (logical sector) on the disk. To stop a machine booting a incorrect system disk each IPLPRO is prefixed with byte. Sharp used 01 for MZ80B 02...
by S_U_C
Fri Nov 19, 2021 1:00 pm
Forum: Hardware
Topic: MZ700 not booting
Replies: 10
Views: 5163

Re: MZ700 not booting

Have you tried pressing the manual reset button on the rear of the machine? The Z80 requires a short low pulse to reset, and is generated on power up by charging a capactor which may have failed. The video circuit runs independantly and desplays 1000 bytes of the VRAM. The Z80 only overwrites the da...
by S_U_C
Wed Nov 03, 2021 3:16 pm
Forum: Hardware
Topic: MZ700 video problem
Replies: 25
Views: 19729

Re: MZ700 video problem

Yes and no. It only scans the keyboard and displays a symbol on the screen if a key is pressed. Normally a space is displayed, if there is a stuck key(s) then a symbol is displayed but the symbol changes when another key is pressed. I am not using any stack area, no CALLs or PUSHes used, the SP reg,...
by S_U_C
Mon Nov 01, 2021 11:33 pm
Forum: Hardware
Topic: MZ700 video problem
Replies: 25
Views: 19729

Re: MZ700 video problem

The screen full of random characters on power up that is different each time you power up is the norm and suggests that the CPU is not running as the screen is cleared by code. A faulty M-ROM or no M-ROM normally produces a repeating pattern or vertical lines. The CPU needs a automatic power up rese...
by S_U_C
Sun Oct 10, 2021 4:05 pm
Forum: Hardware
Topic: MZ-80K displaying garbage chars on screen
Replies: 12
Views: 5620

Re: MZ-80K displaying garbage chars on screen

You reported that pin 26 is low, look at the power on reset circuit.
The Z80 only needs a short low pulse to reset itself.
It must he high for the Z80 to run.
by S_U_C
Mon Sep 20, 2021 11:51 am
Forum: Hardware
Topic: MZ-80K displaying garbage chars on screen
Replies: 12
Views: 5620

Re: MZ-80K displaying garbage chars on screen

Hi, this is the stardard cpu not running screen display as the Z80 clears the screen using code. As you said, same result if no cpu fitted. First try a manual reset, a quick short on pin 26 Z80 to ground (0V) as the reset circuit may have failed. If you have a logic probe check to see if there is a ...
by S_U_C
Fri Aug 27, 2021 5:37 pm
Forum: Hardware
Topic: MZ-80K where to start to repair
Replies: 17
Views: 7130

Re: MZ-80K where to start to repair

The video is a self contained unit consisting of a video ram driven by an binary counter the ouput of the video ram + binary counter drives the CG ROM, and output of thr CG ROM is serialised to produce the display. The 12 volts also powers the dynamic ram on the MZ80K so these could be cooked if sup...
by S_U_C
Tue Jul 27, 2021 9:02 am
Forum: Other
Topic: Text To Speech
Replies: 23
Views: 13952

Re: Text To Speech

Hi, It crashes due to there is no code a $C000 for the USR() call, there are no data POKES to, or a LIMIT set to protect the $C000 area. From the listing “USR($C000,O$), I think the program refers to the JAMAR Speackeasy (the micro speech module) that plugs in to the printer/plotter connector. The c...