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| [153] 6520 vs 6522 http://forum.6502.org/viewtopic.php?f=7&t=408 |
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| Author: | apple2man [ Wed Mar 27, 2002 1:40 am ] |
| Post subject: | [153.1] 6520 vs 6522 |
I'm trying out a project from an old design that used a 6820 (aka 6520) PIA and I'm wondering if the 6522 will work in its place? I know there are extra registery addresses, but if those are ignored, will the 6522 work in place of the 6520? Thanks, Vince |
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| Author: | GARTHWILSON [ Wed Mar 27, 2002 4:00 am ] |
| Post subject: | [153.2] 6520 vs 6522 |
I'm very familiar with the '22, having used it a lot for a wide range of things. (See the "Tip of the Day" topic in this forum, which has lots of tips about using the '22.) However I've done very little with the '20-- or actually the '21, which is the 6520's CMOS equivalent. This '21 was on a commercially-made STD-bus SBC which also had a '22. Since the '22 is so much better, I'm sure the only reason they had both on the same board was to run legacy software that required the '20. As far as I can tell: The only advantages the '20 might have over the '22 are the additional chip-select line, and a separate IRQ output for each port. In most cases, these are negligible advantages. Otherwise, the '22 can do everything the 20 can, plus a lot more. The '22 has the counter/timers and synchronous serial port, all with various operating modes. The '20 only has the two parallel ports-- nothing else. The 6522's pin-out is slightly different from that of the '20, so it cannot be considered a drop-in replacement. In addition, software written for the '20 will have to be modified to do the same job on the '22. Certain operations are just a little more awkward on the the '20. For example, before reading or writing with RS0 low, bit 2 of the appropriate control register must first have been written in order to tell it if you want to access the data direction registers or the ports themselves. Separate addresses in the '22 simplify this. Garth |
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| Author: | apple2man [ Wed Mar 27, 2002 9:53 am ] |
| Post subject: | [153.3] 6520 vs 6522 |
Are the 6520's still available? If so, anybody know where? |
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| Author: | GARTHWILSON [ Wed Mar 27, 2002 1:53 pm ] |
| Post subject: | [153.4] 6520 vs 6522 |
They're $3.89 at Debco Electronics ( www.debco.com ) |
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| Author: | apple2man [ Wed Mar 27, 2002 6:06 pm ] |
| Post subject: | [153.5] 6520 vs 6522 |
Thanks! Another good source for IC's! |
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| Author: | esarintul1 [ Thu Feb 13, 2003 8:28 am ] |
| Post subject: | [153.6] 6520 vs 6522 |
Hi, i must have 80 of them (eighty !!) but i live in France..... René. |
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| Author: | gyorka [ Wed May 14, 2003 6:33 am ] |
| Post subject: | [153.7] 6520 vs 6522 |
you may try to buy them from transfer multi electronic in poland, they have them for about 3 euro - but this is 6521, and as far as i remember it is 2mhz version only.. cheers, candle |
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