Search found 98 matches

by MCes
Fri Jun 23, 2017 10:55 am
Forum: Hardware and Tech
Topic: I/O Addresses
Replies: 8
Views: 188

Re: I/O Addresses

Thanks for your words... No, I haven't a blog but you can find on this forum some ideas of mine. It's only a theoretical circuit, but it could near to be working: IMG_0003.GIF Q6 out of registered SIPO and it's negation (/Q6: Q6 via NOT gate) will generate the 2-bits for comparing with IO2 and IO3 l...
by MCes
Fri Jun 23, 2017 12:27 am
Forum: Hardware and Tech
Topic: I/O Addresses
Replies: 8
Views: 188

Re: I/O Addresses

Ok, try to follow my idea...... Target: a way to permit at software to set the bank address of the cartridge. Immagine:periferics or memory expansion (RAM/ROM) use every decoded lines (I/O2, I/O3, /BLKs, /RAMs...) My solution: take a serial in parallel out (SIPO) schift register that has this input:...
by MCes
Thu Jun 22, 2017 11:51 pm
Forum: Hardware and Tech
Topic: Game cartridge faulty from new
Replies: 5
Views: 110

Re: Game cartridge faulty from new

Cover the eprom window!
It's true that sunlight need years for damage the bytes,
but I destroyed an eprom (it will be un-reprogrammable!) taking a macro with my camera..... WITH FLASH!!!!!!
The UV inside the flash light destroyed my EPROM!
by MCes
Tue Jun 20, 2017 12:12 pm
Forum: Hardware and Tech
Topic: Another problem - image tuning via pot
Replies: 3
Views: 110

Re: Another problem - image tuning via pot

if your monitor has the tuning "sharp" try to reduce its value
by MCes
Sun Jun 18, 2017 2:00 am
Forum: Hardware and Tech
Topic: Recommended fuse rating for 9VAC PSU
Replies: 17
Views: 214

Re: Recommended fuse rating for 9VAC PSU

inside PSU there are some components that have to store energy, at powering on this empty components have to be filled of energy to reach the normal working level, in this moment a current peak is reached ONLY onto 220V line (the line protected by fuse...). No strange voltages outputted by PUS (risi...
by MCes
Sun Jun 18, 2017 1:30 am
Forum: Hardware and Tech
Topic: Recommended fuse rating for 9VAC PSU
Replies: 17
Views: 214

Re: Recommended fuse rating for 9VAC PSU

remember that "T" means "timed" (slow blow) because powering it on there are a natural peak of current (transformer magnetic field and filter capacitors charging),
so you have to put a "T" type or fuse could blow during a switching on...
by MCes
Fri Jun 16, 2017 7:39 am
Forum: Hardware and Tech
Topic: I/O Addresses
Replies: 8
Views: 188

Re: I/O Addresses

better: use an inexpensive 8bit comparator 74LS682 and use as input: 0: I/O2 1: I/O3 2: A9 3: A8 4: A7 5: A6 6: A5 7: A4 74LS682 has internal pull-up: only dip switch have to be added to be compared, remember that dip sw. 0,1 can't be open or closed both of them at the same time, or use a deviator t...
by MCes
Fri Jun 16, 2017 12:20 am
Forum: Hardware and Tech
Topic: I/O Addresses
Replies: 8
Views: 188

Re: I/O Addresses

my suggestion: put a little 2 position switch for choosing between I/O2, I/O3 then this selection has to be inverted (a NOT gate, or equivalent) and the signal can feed the pin 3 (A=B in) of a 74HC85 (a 4 bit comparator): pin 6 (A=B out) will be the decoded line for your registers address (active H,...
by MCes
Mon Jun 12, 2017 12:25 am
Forum: Buy, Sell, and Trade
Topic: 1540 Drive
Replies: 14
Views: 307

Re: 1540 Drive

Where are you?
How much for sending it to Italy?
by MCes
Mon Jun 05, 2017 8:29 am
Forum: Buy, Sell, and Trade
Topic: WonderVIC
Replies: 8
Views: 533

Re: WonderVIC

unfortunately 6561 is soldered
by MCes
Thu Jun 01, 2017 12:18 am
Forum: Buy, Sell, and Trade
Topic: WonderVIC
Replies: 8
Views: 533

Re: WonderVIC

What is the purpose of the alternate kernel in this mod? in my prototype the "alternative kernal" is a modified jiffydos, the modify skip the cartridge auto start: it's useful for copying cartridges or if you had a cartridge image on ram but you want not start it (for a new software sessi...
by MCes
Mon May 29, 2017 1:49 am
Forum: Buy, Sell, and Trade
Topic: WonderVIC
Replies: 8
Views: 533

Re: WonderVIC

New price!
by MCes
Fri May 05, 2017 12:54 pm
Forum: Hardware and Tech
Topic: Combining my Vics to make a good one?
Replies: 17
Views: 372

Re: Combining my Vics to make a good one?

NOTE: 6560 and 6561 are NOT swappable: they are feeded with different xtal clock frequency that is in relationship with the colour portant frequency, so the relationship between xtal input clock and generated system clock are different into two chips (and probabilly 6561 can't run up at xtal clock ...
by MCes
Wed Apr 12, 2017 12:01 pm
Forum: Hardware and Tech
Topic: 1541 drive and faulty 6522 chip
Replies: 25
Views: 290

Re: 1541 drive and faulty 6522 chip

From all I'm reading, I am surprised nobody has looked at the roms. If it starts ok when it's turned on, then I might lean towards the rom that is lower in memory first. If I remember well the firmware check the ROM and if they have problem (checksum error) the red led continuously flash, if the pr...

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