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RE: [N8VEM-S100:874] 1.1k 10-pin Resister Pack supplier (or alternative values)?
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- Subject: RE: [N8VEM-S100:874] 1.1k 10-pin Resister Pack supplier (or alternative values)?
- From: "John Monahan" <mon...@vitasoft.org>
- Date: Thu, 21 Jun 2012 06:29:35 -0700
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Just use 1K
From: John Monahan Ph.D
From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On
Behalf Of Paul Birkel
Sent: Wednesday, June 20, 2012 10:37 PM
Subject: Re: [N8VEM-S100:874] 1.1k 10-pin Resister Pack supplier (or
Thanks Tom, John. Doing the verification part here before the testing :->.
We need to collect these sorts of "tweaks that work" for the various boards
in appropriate locations methinks.
John: While I've been reading up on the various calculations regarding the
selection of o.c. pullups and fanout/in calculations (Wilcox Section 3.1.1
is quite good) I haven't found anything specific on the selection of
open-input pullups. Recommendations?
On Wed, Jun 20, 2012 at 11:38 PM, John Monahan <mon...@vitasoft.org> wrote:
> 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
> e-mail: mon...@vitasoft.org
> Text: mon...@txt.att.net
> -----Original Message-----
> From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com]
> On Behalf Of Paul Birkel
> Sent: Tuesday, June 19, 2012 10:32 PM
> To: n8vem...@googlegroups.com
> Subject: [N8VEM-S100:870] 1.1k 10-pin Resister Pack supplier (or
> alternative values)?
> 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.