NMB First Generation

Overview

The first generation was NMB first iteration of NMB keyboards that were produced under the 725 series of keyboards. These keyboards were set to rival other manufacturers like IBM but at a lower cost

The first generation of NMB Hi-Tek 725 series keyboards have the following seven main components:

  • Switches

  • Keycaps

  • Upper Case

  • Mounting Plate

  • PCB

  • Back Plate

  • Cable

Switches

The first generation of keyboards used the following variants of switches below.

Early keyboards used the very first version of the 725 series of switches, often referred to as "Gundam" due to the similarity of shape compared to the head of a Gundam like the Japanese anime. Gundam switches can be identified by the curved contact openings.

Later keyboards used the more common variant with rectangular content opening with either round or square eye. Round eye versions of rectangular mouth switches lack the additional plastic on the sides that would allow later generational keycaps to latch into the switch. Unlike the round eye switches, square eye have the additional plastic that allows keycaps with latching hooks to lock into the switches.

In addition, to regular linear square one eye switches NMB introduced LED switches. These switches allow a 3mm LED to be incorporated into the switch due to the triangle nature of the switch. Therefore, the keycaps for LED switches are unique and have a center bar at one edge of the cap so that the cap is secured properly to the switch.

Early Switches(Gundams)

Later Switches

Keycaps

The keycaps are made out of PBT with dye-sublimated legends.

Early XT keyboard versions used an ABS spacebar that can be identified by their often yellowed spacebar. Later models come with a PBT spacebar.

The keycaps on generation one keyboards are pressure fit and lack the clips that can be found on later generations of NMB keyboards. Keycaps in the first generation have shiny sides of the keycaps.


Upper Case

The upper case consists of a single molded piece of beige plastic that is texture-coated. The plastic color is off-white with a yellow tinge.

The case contains eight mounting points that are threaded bosses. The threaded bosses are brass for earlier models whereas later models used screws that threaded into the upper case plastic.

The bosses that are found on the sides of the case are used to attach the switch plate assembly to the upper case. The bosses on the upper and lower edges of the case are used to attach the backplate to the upper case. The retractable feet are hooked into the upper case through a pig tail-like wire that hooks into the upper case. This provides resistance when the feet are extended and locked into the outward position.


Back Plate

The backplate consists of a single plate with a V-shaped trough that is offset from the top edge of the upper case and runs laterally parallel to the top edge. The backplate is black. Early models of the first generation keyboards contain a steel backplate whereas later models used plastic for the backplate. Note that earlier models contain a grounding screw in the back plate where later models do not.


Case Markings

Stamped date codes can be found on the back plate with white paint. The date codes follow the following format: MMYY. Along with the date code is a serial number sticker that is between 5-6 digits in length. Later models may contain a part number sticker that lists the part number, revision, and code. Some examples also might contain a "Made in Thailand" sticker.


Switch Plate

The switch plate is made out of stamped steel. The plate is bent on either so that it can be mounted to the upper case. The plate is painted with a thin layer of black paint. The paint is then protected by a thin layer of oil to prevent rust.


PCB

The PCB is a double-sided PCB with all traces on the backside of the PCB. The controllers found on the PCB vary, some later models have been found with both Toshiba and Mitsubishi controllers.


Cable

5 Pin Din

The cable is approximately 1 meter long for the coiled variant and stretches up to 2 meters easily. It contains a molded 5 pin din connector with 6 pin headers using a molex connector on the PCB. Earlier cables can be found with a separate ground lead which connects to the grounding screw that connects the upper case and the back plate together. Later cables come with 6 conductors but lack the ground lead. Earlier cables are thicker than the later ones.

The cable contains a molded block that is press-fitted into the upper case to keep the cable secure.


RJ-11

The coiled cable is normally 30 cementers long with RJ connectors on either end. Keyboards that use the RJ cable have a RJ-11 female jack in place of the molded block that would have been used for the 5 pin din cable.


Variants

XT

Top

Switches

PCB

Back

Internals

Top Case Inside

Credit: Engicoder

AT

Top

Switches

Bottom

Internals

Credit: Engicoder

Other Variants

Tandy 1200HD

Tandy 1200HD

Model Number

Corona Data-PPC-400

Corona Data - PPC-400

Advertisements / Manuals

Hi-Tek-725-IBM-Compatible-Keyboards-flyer.pdf
Hi-Tek-725-SL884-PC-83-PC-84-Borchure.pdf
Hi-Tek-SL585-AT-84-Product-Sheet.pdf
Hi-Tek-Keyboards-Marketing-Folder.pdf
Hi-Tek-725-PC-83-PC-84-Keyboards.pdf
Hi-Tek-725-PC-83-Keyboard-Specifications.pdf
Hi-Tek-725-AT-84-Keyboards.pdf