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Firehose Replacement Thoughts


CyanKi

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Hi All,

Thought I'd ask before trying to recreate the wheel. LOL Any thoughts/experience on whether bluetooth could be used to replace the bulky PEB connection to the console?

I tried searching the forum, but didn't see anything related to this topic. Sparkfun had some modules at one point and thought it might be fun to see if it would work.

Thanks!

Robert

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IN a word, no.

 

You *might* be able to create a specialized serial connection to replace it, but it would require probably FPGAs on both sides, and a VERY fast clock speed.  The idea would be to marshall all of the PEB signals at the TI very quickly and then shift them out via a serial line to the same kind of thing on the PEB side, which would then unmarshall them and present them to the PEB as before.  Then, close to the end of the cycle, do the reverse, taking into account that certain lines need to be handled special because they are IO lines (address never needs to be sent back, but data does on a read cycle, and the CRU stuff needs to be handled special as well).

 

Possible, yes.  practical, less so. 

 

A better bet would be to shrink all of the PEB functionality and move it to the TI, like TIPI and other solutions do.

 

Jim

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(I'm moving this to the main 99/4A subforum.)

 

As a less drastic solution, I've often wondered if the "firehose" cable could simply be replaced with a smaller and thinner cable, such as a rounded SCSI peripheral cable (one with enough conductors, of course).  That would allow you to use an already-existing cable assembly; in that case, all you'd need is a small adapter on the 99/4A side, and possibly a new expansion card on the PEB side.

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@matthew180 has some ideas on this.

 

This topic has come up in the past and gigabit Ethernet was one idea but it would be either just too slow or just barely fast enough.  I think UW-SCSI might work, either flat cable or the HD-68 external.  Maybe even VHDCI.  Ideally that would eliminate the requirement of active conversion like piping through gig-E, Fiber Channel, USB-C, etc.

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Though not "wireless," there's a simpler hardware method. Just get or make a ribbon wire extender with proper crimp connectors to fit the console and PEB. My dad and I scored a couple in the '80s that were sold pre-made, in a nice 36" length that has always worked well to park the PEB and firehose as far out of the way as I wish. A more recent reincarnation was only 18 inches long and had to use a gender changer finger-board at the PEB end because the one-piece ribbon-to-male connector on mine is now unobtainium.

-Ed

firehoseribbon.jpg

firehoseadapter.jpg

PEBmaleRibbon.jpg

Edited by Ed in SoDak
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I've had good luck with << THIS CABLE >> over the years.  It's allowed me to plug it in the side of the ti and wrap it under the TI and out the back, thus hiding the "firehose" behind the monitor.  One thing to notesome people with a specific Myarc card, I cannot remember which, have reported problems.

L1172.jpg

 

I'm sure everyone has seen this image before, but not having that blasted thing hanging out the side and taking up valuable desk space has been wonderful.

ti.jpg

 

 

 

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2 hours ago, OLD CS1 said:

@matthew180 has some ideas on this.

 

This topic has come up in the past and gigabit Ethernet was one idea but it would be either just too slow or just barely fast enough.  I think UW-SCSI might work, either flat cable or the HD-68 external.  Maybe even VHDCI.  Ideally that would eliminate the requirement of active conversion like piping through gig-E, Fiber Channel, USB-C, etc.

I made an interface on the side port to serialize bus signals into an FPGA (you saw me debugging it...) I got it down to 16 lines.

 

I compressed the address and control lines (24) into 8 lines. The bi-directional data bus I left as parallel 8 lines.

 

So the whole thing fit in 16 lines of the FPGA. A full 4A interface would have taken 34.

 

Here's the breakdown:

 

I connected the 4A address bus to 2 8-bit shift registers, LVC165. An FPGA clocked these registers at 25 MHz. I tried for 50 MHz but it was not reliable. Thus, it took 8*40 = 320ns to read the two shift registers. 3 lines were required for this.  Since the 4A external memory cycle is 1000ns, this was fast enough. 

 

Legal combinations of control lines RESET, MEM, DBIN, WE, CRUCLK, CRUOUT were encoded by a CPLD into a 3 bit state (reset, memory address, memory read, memory write, cru read, cru write 0, cru write 1)

 

I used 8 bits for the bidirectional data bus. The last two were for A15/CRUOUT and CRUIN. A15 served two purposes: CRU and refining the memory access state. CRUIN was gated onto the bus during cru read state only. 

 

This crazy project consumed most of my hobby time in 2018 and was ultimately not super great. I was able to read/write from external RAM, using test programs in Mini Memory. I started to try out a SAMS type pager. But every now and then it would glitch on the odd byte or something.

 

OLD CS1 got me thinking of gigabit ethernet.   I didn't think it would work out -- would you have a transceiver at each end constantly updating state? My device reacted to state changes in 10-20ns. 

 

 

 

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I bumped my old thread from 2014, just 'cause it touched many of these lines of thinking. What kicked it all off back then was my bragging up my simple little cable.

 

What I love reading about are the high-tech approaches versus my row of wires. The "horsepower" differences are like a 1974 Ford Pinto kicking ass against a 2020 Dodge Challenger. But look what you get as a bonus - a prediction of the Tipi and a possible pathway to a cross-platform networked PEB.

 

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I tend not to talk about hardware I'm not working on (or done building), but I have thought about a fire-hose replacement from time to time.

 

The main problem is speed.  Even though the 99/4A seems really slow compared to today's computers, the fire-hose and PEB bus operate at the full CPU bus speed of about 3.3MHz, or 333ns.  When you consider that kind of speed, things like USB and networking fall short because the system-bus will not tolerate any latency in a bus transaction.  Memory accesses in the 99/4A do introduce a wait-state for 16-to-8 bit memory access, but that speed is still fast, and it has been proven that most memory in the old systems was fast enough to operate with the wait-state generator bypassed.

 

Long story short, to make the console to PEB cable smaller you really need to reduce the number of cables, and to do that you need to serialize the bus.  Luckily the computer world is crazy with high speed serial buses these days, and we can ride that wave of cheap ICs and cables.

 

If I was going to make such a cable, I would probably use a pair of these (18-Bit Bus LVDS Serializer/Deserializer - 15-66 MHz):

 

https://www.ti.com/product/DS92LV18

 

Two transmit and two receive channels could be run over a stock digital video cable (like DVI or that other one that I won't mention), or even a USB-C cable.  It would need to be run somewhere around 30MHz or so to have some margin, but that is well within the capability of these ICs.  Some buffers to control direction and bus contention, and you could probably do the whole thing with non-programmable ICs (no FPGA, CPU, or microcontroller needed).

 

You would have to know WTF you are doing with high-speed serial electronics and PCB layout though, this is not a low-speed kind of circuit.  But the result would be a single small cable between the console and PEB.  However, these days it might be easier to just put the 99/4A onto a single PCB and stick it into the PEB (which I think has been done in the past).  You would have to do something about the cartridge port though.

 

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I can think of two ways it was fully eliminated in the past: the Rave PE2 allowed the motherboard to be installed into the case and brought the cartridge port and keyboard interface to the outside, and the SNUG 99/4P, which actually needed three PEB cards to replicate the entire console (although it also gave a lot more GROM space, AMS memory, and upgraded the system to 80-column video). Of course, there was also the mostly compatible Myarc Geneve 9640 as well, so that would make a third solution.

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*still holds that a shielded peripheral cable, with appropriate adapters on the ends, would do just fine*

 

Say, this DB50.

https://www.monoprice.com/product?p_id=781&gclid=EAIaIQobChMIw6XPpbuc7AIVDovICh3dPgrdEAQYBSABEgLPzPD_BwE

 

Would allow you to intersperse some additional ground lines inside the bundle, and thus have slightly better signal fidelity.  Nice round cable would be easier to manage with cable management, and the connector is quite robust.

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  • 3 weeks later...

No.  If anything, extra waitstates were introduced to deal with the slow speed of extending the bus that far, and dealing with the repeater baked inside the PEB interface card.

 

 

I just feel that a round (and properly shielded) cable would be easier to have effective cable managment with, and that you can get 50 conductor cables that are already industry standard, with standard connectors.  Devising a proper port adapter dongle for either end would solve the problem neatly.

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9 hours ago, towmater said:

I don't know what's inside that rubber mess... but what about just cutting two-feet or so out of the cable and making it a little less cumbersome? Is the length important for some "propagation" reason?

It's not... people have used all kinds of cables over the years to replace that thing. The cable as built has buffers at each end to drive the signal, but there are no timing issues that I'm aware of. The TI's memory cycle is pretty slow.

 

Inside the rubber is literally just a shielded ribbon cable. The big blocky "foot" that plugs into the console has buffers for that end of the cable.

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On 10/21/2020 at 11:21 AM, Tursi said:
  On 10/21/2020 at 2:06 AM, towmater said:

I don't know what's inside that rubber mess... but what about just cutting two-feet or so out of the cable and making it a little less cumbersome? Is the length important for some "propagation" reason?

I'm cutting mine up rt now!!

Ok, just kidding.. but.. here is another question.

Can that complete connector, the one on the side of the TI, be placed in the PEB and wired to the console by round cabling?

I wonder how and where to put it.maybe on the inside case lid?

 

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25 minutes ago, GDMike said:

I'm cutting mine up rt now!!

Ok, just kidding.. but.. here is another question.

Can that complete connector, the one on the side of the TI, be placed in the PEB and wired to the console by round cabling?

I wonder how and where to put it.maybe on the inside case lid?

 

 

I remember they did sell round cabling with the proper amount of conductors, but connectors were scarce.  If you did do that, it would not be too practical as your cable length could not be too long without inducing issues.  The maximum length for extensions over the years seems to have self-limited to 18 inches or less, I'm guessing there is a good reason for this.  

 

My solution was to hide the firehose connector behind the monitor and then use an extension coming in from the back and twisted underneath the console and plugged into the side.  Of course as you read further up others have varying opinions.

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28 minutes ago, GDMike said:

Can that complete connector, the one on the side of the TI, be placed in the PEB and wired to the console by round cabling?

 

You need that connector where it is. It contains circuitry for conditioning weakened (due to distance and shielding) signals to/from the PEB. Think of it like the shortstop relaying a throw from centerfield to the plate. You would not put the shortstop in centerfield with the fielder to throw all the way home—kind of defeats the purpose.

 

...lee

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On 10/4/2020 at 3:09 PM, OLD CS1 said:

@matthew180 has some ideas on this.

 

This topic has come up in the past and gigabit Ethernet was one idea but it would be either just too slow or just barely fast enough.  I think UW-SCSI might work, either flat cable or the HD-68 external.  Maybe even VHDCI.  Ideally that would eliminate the requirement of active conversion like piping through gig-E, Fiber Channel, USB-C, etc.

I think that was the thought with the 99/8 and one of its prototype connectors.  Right angle Centronics type connector, thick round cable to PEB card.  That might be doable.

 

Most of the part of the “foot” is for stability.  The buffers don’t take much space.  Maybe a daughter card and adapter to Centronics and the same on the other end - the Flex cable card could be replaced too as part of this. 
 

Daughter/EDGE adapter card with buffers to Centronics connector.  Centronics 50 pin connector to Centronics 50 pin on new Flex Cable interface card, which has same buffers, etc, just a Centronics jack.

 

Challenges to this include finding shielded cable and splicing the connectors on the 50 pin cable.  Ask any 1A2 phone guy that still has the tool to put a right angle Centronics onto wire - it’s an art.  There’s also the soldering way.  

 

 

 

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1 minute ago, acadiel said:

I think that was the thought with the 99/8 and one of its prototype connectors.  Right angle Centronics type connector, thick round cable to PEB card.  That might be doable.

 

Most of the part of the “foot” is for stability.  The buffers don’t take much space.  Maybe a daughter card and adapter to Centronics and the same on the other end - the Flex cable card could be replaced too as part of this. 

 

I know not all are like this, but I have a couple of Speech Synthesizers which hold on to the console like it is life support.  If that were more consistent, this could be done in a case no larger than the SS case.  The 25-pair Centronics/Amphenol angle connectors for phone systems are quite compact, and the cabling is shielded.  Not entirely flexible but enough, I would think.

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13 minutes ago, OLD CS1 said:

I know not all are like this, but I have a couple of Speech Synthesizers which hold on to the console like it is life support.  If that were more consistent, this could be done in a case no larger than the SS case.  The 25-pair Centronics/Amphenol angle connectors for phone systems are quite compact, and the cabling is shielded.  Not entirely flexible but enough, I would think.

That might actually work.  A replacement PCB for the speech synth, including the speech chips, buffer chips, and the Centronics port.  

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