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RE: [N8VEM-S100:870] 1.1k 10-pin Resister Pack supplier (or alternative values)?
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- Subject: RE: [N8VEM-S100:870] 1.1k 10-pin Resister Pack supplier (or alternative values)?
- From: "John Monahan" <mon...@vitasoft.org>
- Date: Wed, 20 Jun 2012 20:38:56 -0700
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Paul this question has come up before. There is nothing special about the
1.1K value of the pull-up resistors for the TTL circuits. 1K will be fine,
as would the more common 1.2K types. Jameco used to sell 1.1K's but no
longer do. The choice of value for pull-ups like that is a balance between
noise immunity (low values, ~1K) to power utilization (high values ~2K or
even 4.7K). Other factors are signal pulse width and fan-out.
From: John Monahan Ph.D
From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On
Behalf Of Paul Birkel
Sent: Tuesday, June 19, 2012 10:32 PM
Subject: [N8VEM-S100:870] 1.1k 10-pin Resister Pack supplier (or alternative
The S-100 MSDOS Board, Z80A Master CPU Board, and Serial I/O Board all
specify the use of a 1.1k 10-pin Resister Pack.
This seems to be an uncommon part. Is there a recommended supplier?
Alternatively, is the value critical in these three board-uses?
The S-100 MS-DOS Board uses a pair of packs (RR7/8) as input pull-up
resistors on the two 74LS165 address decoders. The Z80A Master CPU Board
similarly uses three packs (RR3/4/7) as input pull-up resistors on its three
74LS165 address decoders. It seems to me that in this use the values are
fairly non-critical. What is the recommended, commonly-available,
alternative resistor value?
The Serial I/O Board is a bit more complicated. It uses a single pack
(RR1) which connects to PU1K-A thru PU1K-I.
1. PU1K-A/B/C are used on the Z8530 UART_INT*, UART_IEI, and UART_INTA,
apparently as input pull-ups.
2. PU1K-E/F are used as pull-ups on two outputs of a open-collector
74LS06N (the other 4 outputs are spares).
3. The remaining 4 pack-resistors are spared.
Given this mixed-use, what would be the recommended, commonly-available,
alternative resistor value? Or should I consider hand-wiring single
resistors in each case -- and then what would be the recommended values in
each case (UART input pullups; o.c.