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Apple Techstep I have almost all of the ROMs here and some info!

jajan547

Well-known member
I have to wonder if the designers of the TechStep intended for different connections to be released in the future, considering that the entire IO section on the TechStep is detachable.
I think so, so I have an issue everything connectors, chips, sockets etc. is a perfect match however, I think I ordered the wrong size parts and I have no clue which to order for the component on the bottom side of the board(s). I have attached pictures. Can anyone provide a link?
 

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jajan547

Well-known member
Also news ROMs for CPU Tests Vol 1.1.1, CPU Tests Vol 2, and SCSI HD Tests Vol 1.0 are all revision 1 boards which means they need a AM27C512 and all others (CPU Tests Vol 3 and CPU Tests Vol 4) are the newer revision board MX27C1000.
 

SuperSVGA

Well-known member
I think so, so I have an issue everything connectors, chips, sockets etc. is a perfect match however, I think I ordered the wrong size parts and I have no clue which to order for the component on the bottom side of the board(s). I have attached pictures. Can anyone provide a link?
If I measured correctly it should be an 0805 resistor. Looks like you have size 0402.

Anything from here should work:
https://www.mouser.com/c/passive-co...05&resistance=10 kOhms&instock=y&sort=pricing
 

jajan547

Well-known member
Well good news and bad news boards line up perfectly and all components are a match, however I ran into troubles. The pin header is flipped the wrong way and as such it is off centered, I figured eh I'll try and solder it flipped and test it and the tech step refused to boot, when I removed it and reinserted the correct original ROMs all was okay so I'd imagine there is a built in safety feature there. As it stands now I am unable to test and now need to order the revised new Gerbers that hopefully you can fix real quick and then we can test.
 

SuperSVGA

Well-known member
Gerber has a issue with the connector and as did all of the boards I believe it's the wrong way around.
Yeah it looks like the custom footprint came out backwards. My boards were held up due to a four layer board that was in the same order, but they finally arrived. I was able to put one together by bending the pins, and it does appear to work.
IMG_3138.jpeg
I'll have to correct the footprint for the connector as well as make changes for compatibility for some newer PROMs.

Also if possible can you make a through hole revision for the plcc socket.
I'll see if I can find one that fits. The ones I have are too tall compared to the SMD counterparts, so the case would no longer fit if used.
 

jajan547

Well-known member
Yeah it looks like the custom footprint came out backwards. My boards were held up due to a four layer board that was in the same order, but they finally arrived. I was able to put one together by bending the pins, and it does appear to work.
View attachment 38918
I'll have to correct the footprint for the connector as well as make changes for compatibility for some newer PROMs.


I'll see if I can find one that fits. The ones I have are too tall compared to the SMD counterparts, so the case would no longer fit if used.
I can link the ones I use that appear to sit lower. Also what ROM image and ROM board did you go with I see the surface mount chip so I'm assuming later ROM board. Anyways I'll try bending the pins to make it work now and I'll let you know how it goes, after you tinker around with the Gerbers and fix or rework things a bit feel free to upload the updated Gerbers and I'll order some more and try them out. Thank You again for all of the hard work!
 

Skate323k137

Well-known member
I can link the ones I use that appear to sit lower. Also what ROM image and ROM board did you go with I see the surface mount chip so I'm assuming later ROM board. Anyways I'll try bending the pins to make it work now and I'll let you know how it goes, after you tinker around with the Gerbers and fix or rework things a bit feel free to upload the updated Gerbers and I'll order some more and try them out. Thank You again for all of the hard work!
Where are you getting your PCBs fabricated? I've been waiting on an order from Gerber Labs for some time, though to be fair it was mainly delayed by the lunar new year.
 

jajan547

Well-known member
Where are you getting your PCBs fabricated? I've been waiting on an order from Gerber Labs for some time, though to be fair it was mainly delayed by the lunar new year.
I went through JLCPCB and turn around time was very fast even with colored boards. I think if you get stock greens ones and choose 3-5 day shipping with DHL it comes out to $22
 

Skate323k137

Well-known member
I went through JLCPCB and turn around time was very fast even with colored boards. I think if you get stock greens ones and choose 3-5 day shipping with DHL it comes out to $22
Thanks, I'll probably give them a try next time. Gerber isn't even answering my emails to ask what shipping service they used, let alone provide a tracking number, so I'm not super impressed.
 

jajan547

Well-known member
Let us know how it turned out. As for the pin connector I know this sounds silly but I cant get the pins bent the right way so I'll just play it safe and wait for some updated gerbers, hopefully. I think SuperSVGA did an awesome job and all they need is some minor tweaking.
 

jajan547

Well-known member
Yeah it looks like the custom footprint came out backwards. My boards were held up due to a four layer board that was in the same order, but they finally arrived. I was able to put one together by bending the pins, and it does appear to work.
View attachment 38918
I'll have to correct the footprint for the connector as well as make changes for compatibility for some newer PROMs.


I'll see if I can find one that fits. The ones I have are too tall compared to the SMD counterparts, so the case would no longer fit if used.
Also JLCPCB is offering $2 for 2-4 layer boards in quantities of 5.
 

jajan547

Well-known member
Yeah it looks like the custom footprint came out backwards. My boards were held up due to a four layer board that was in the same order, but they finally arrived. I was able to put one together by bending the pins, and it does appear to work.
View attachment 38918
I'll have to correct the footprint for the connector as well as make changes for compatibility for some newer PROMs.


I'll see if I can find one that fits. The ones I have are too tall compared to the SMD counterparts, so the case would no longer fit if used.
Were you able to fix the Gerbers? If you did I can go ahead and order new boards. Thanks for all of the work in advance.
 

jajan547

Well-known member
@jajan547 and @SuperSVGA incredible work here. Thank you for doing this!

Did you also dump the X25C02P ROMs or do those just work off the shelf as is?
Those work off the shelf, when I get home later today I can confirm perfect chip matches to it. We have identified at least two modern replacements one is through hole the other is surface mounted.
 

elemenoh

Well-known member
Thanks for the info! Also, what programer and adapter(s) are you using to program the PLCCs and/or SMD chips?

Lastly, I drafted the top enclosure. I'll try to get the bottom done today too and do a test print shortly after.

Screen Shot 2022-03-07 at 10.46.32 AM.png
Screen Shot 2022-03-07 at 10.46.51 AM.png
 

jajan547

Well-known member
The smaller chip doesn’t need to be programmed however the 32pin plcc does and I use a Tl86 plus programmer I program it using a 32pin plcc to I believe 8pin adapter in it. Awesome work on that 3D model it looks like the original, we just need to get the pin connector flipped on all of the gerbers and we should be all good to go, I found a bit of info and I think it’s possible to make a ROM that can communicate with the 128k/512k/plus line as well.
 
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